This walkthrough will guide you through Pokemon Black and White - in terms of gameplay, there are some relatively major differences in characters and locations between versions. Use the menu above to jump between sections; alternatively, if you wish to use the walkthrough from beginning to end, click the 'Next Section' button to advance. Complete Guide to Authentic GBA Pokemon Games! This is my personal guide to telling the Pokemon games for the GameBoy Advance series apart from fake ones! This guide will go over Generation III and (unofficially) Generation III.5. These games include the ever popular Pokemon Ruby, Pokemon Sapphire, Pokemon Emerald, Pokemon Fire Red.
Pokémon Black & Pokémon White are the first games of the long anticipated fifth generation of Pokémon. These games are due for release in Japan in September 18th 2010 and are said to bring about a revolution of Pokémon. .
These games are set to feature the previously established assortment of Pokémon, but will also contain a massive amount, 156 in fact, of brand New Pokémon. These Pokémon are the only ones you will encounter until the main game has been completed
In addition to that, Pokémon Black and Pokémon White take the 3D attributes previously included in Pokémon Diamond, Pearl, Platinum, HeartGold & SoulSilver and take them to new levels by including things like fully 3D bridges and a completely 3D city.
Pokémon Black & White are set in the region known as Unova. Unova is a region far away from the previous regions, requiring you to get there by Boat or Plane. It has a large city called Castelia City, with loads of buildings and sky scrapes for you to explore. Outside of the city and Unova remains to be predominantly industrialised with various factories and train tracks existing in the various areas. As the games are set in a region far away, the main game will not feature any old Pokémon until you have beaten the main story. The games also have you playing as protagonists older than the previous playable characters.
Pokémon Black & Pokémon White are to be compatible in with the games of the previous generation; Diamond, Pearl, Platinum, HeartGold & SoulSilver through the aspect of the game known as the PokéTransfer so you can complete the Pokédex. In addition to this, there is a method called the Relocator which works only for a certain few event Pokémon. Through this, some event Pokémon can be traded over to these games to unlock new things such as the Monster Fox Pokémon, Zoroark.
Features
There are numerous featurres introduced within the game. First, in battle, there are two further methods of battle; Triple Battle & Rotation Battles. Both of which have you send out three Pokémon at once in order to battle with varying mechanics within it. In local wireless and over WiFi, there is also the Wonder Launcher which is a function that allows you to use items during battle, but at a cost. In battles, the camera is also dynamic, zooming in and out on the Pokémon while they move in a variety of animations
Much like how Gold & Silver introduced the concept of the Day/Night cycle, Pokémon Black & White introduce the concept of Seasons. These seasons change a variety of factors including Wild Pokémon, location aesthetics and even the background music. The seasons rotate at the start of every month so you don't need to wait long until the next one.
The games also introduce a variety of new multiplayer aspects including the Xtransceiver, a DSi & 3DS exclusive feature, that allows for video chat with you and your friends. In addition to that, the games can now connect to the Internet for access to a site called the Pokémon Global Link. The Global Link allows you access to Random Matches on the Internet, capable of being ranked based upon your performance, as well as a section called the Dream World which will allow you to obtain non-Unova Pokémon, some of which have new abilities, and items that also cannot be obtained in Unova such as Berries. In addition to this, the games also have the Entralink feature which has you visit a friend's game and complete certain missions in order to get various power ups which last a short time in the main game.
The game's story features you having to stop Team Plasma, a team who, unlike previous teams, want to do good and intend to stop what they perceive the slavery of Pokémon caused by trainers. In addition to this, you also have to travel the region in order to get 8 badges once more.
DSi Enhancments
As stated above, Pokémon Black & White are DSi Enhanced. As such, they will only work on DSis of the same region as the game. However, despite this, there are a variety of new features exclusive to the DSi. First is the Xtransceiver which does allow for voice and video chat between up to 4 friends locally and 1 friend over the Nintendo Wi-Fi Connection. In addition to this, Pokémon Black & White are capable of connecting to the Internet via the WPA encryption as opposed to previous games only being able to connect to WiFi through no encryption, or WEP.
The games can be played on any model of DS
Pokemon Black White Guide
- How EVs Work
- EV Training Tools
- Fifth Generation Changes and Additions to the EV System
- EV Training Hotspots
- EVing for Level 50
Introduction
EV training in Black, White, Black 2, and White 2 has remained mostly identical to the fourth generation games save for a few small changes. The changes are comprised of a new mechanic, new items, and the return of a third generation mechanic regarding the EV reducing berries. The new mechanic is a change to when EVs are applied, with the Pokémon no longer having to level up for EVs to affect the stat. Wings make up the new set of items, giving 1 EV to a specific stat with each use. The fifth generation EV system certainly brought some interesting new tools to ease the odious task of EV training, but let's first revisit the basics of EV training.
How EVs Work
Effort Values, or EVs for short, allow you to further build upon your Pokémon's base stats. They are extremely important in the world of competitive Pokémon battling, as the more EVs you invest in a stat, the higher that Pokémon's stat will be. To really understand EVs, you have to know more about how a Pokémon's stats are calculated.
The following two formulae determine your Pokémon's stats (round down after every set of parentheses):
HP = ((2 * BaseHP + IV + (EV / 4)) * Level / 100 + Level + 10)
Stat = (((2 * BaseStat + IV + (EV / 4)) * Level / 100 + 5) * Nature)
Where:
BaseHP = The Pokémon's base HP
BaseStat = The Pokémon's base stat for your given statistic (Attack, Defense, etc)
IV = The IV value of your Pokémon's stats (anywhere from 0 to 31)
EV = The amount of EVs you invested into your Pokémon's stat (anywhere from 0 to 255)
Nature = The nature modifier for the given stat (0.9, 1.0, or 1.1)
Level = The Pokémon's current level.
There are five basic rules that must be followed and remembered:
Rule 1: At level 100, for every 4 EVs that a Pokémon has in a particular stat, the stat is increased by one point.
This means that if you invest 252 EVs into Attack (the maximum effective amount of EVs, more on that later), your Pokémon's Attack stat will go up by 63.
Here's an example using everyone's new favorite rodent, Victini.
Its base Attack stat is 100, so its maximum Attack at level 100 is 236 (assuming a neutral nature and 31 Attack IVs). However, throw in 252 Attack EVs, and that maximum Attack goes up to a whopping 299.
Stat = (((2 * BaseStat + IV + (EV / 4)) * Level / 100 + 5) * Nature)
Attack = (((2 * 100 + 31 + (252 / 4)) * 100 / 100 + 5) * 1.0)
Attack = (((231 + 63) * 1 + 5) * 1.0)
Attack = ((294 * 1 + 5) * 1.0)
Attack = ((299) * 1.0)
Attack = 299
You should also keep in mind that natures affect stats after EVs are figured in. So, if our Victini had an Attack-boosting nature (such as Adamant), you would multiply its 299 Attack stat by 1.1, bringing us to 328.8, which, after rounding down, becomes 328. Likewise, if we had an Attack-lowering nature (such as Modest), we would multiply the 299 Attack stat by 0.9, which brings us to 269.1, or, after rounding, 269.
In general, it's a bad idea to invest EVs in stats negatively affected by nature, since it undermines much of the EV work that you do in the first place.
Rule 2: EVs invested should always be divisible by four.
Due to how statistics are calculated, this is one very important rule you must follow. Any leftover EVs after you divide them by four are wasted.
For example, if you earned 253 Attack EVs, 253 divided by 4 = 63.25, which is rounded down to 63. Those 0.25 stat points are completely wasted.
Using our formula, we will look at the important part of the equation:
Stat = (((2 * BaseStat + IV + (EV / 4)) * Level / 100 + 5) * Nature)
(EV / 4) = (253 / 4) = (63.25)
And remember to round down, so 63.25 = 63.
Rule 3: Each stat can have a maximum of 255 EVs invested. Any Pokémon can only earn a maximum of 510 EVs.
Keep in mind that because EVs should always be divisible by four, the effective maximum you should invest is 252 EVs.
Because 510 EVs is the absolute maximum, and 252 is the effective maximum per stat, that means you can—at most—max out two stats, leaving you with 6 EVs left over. This allows you to invest 4 EVs into one more stat, and you will always be left with 2 EVs left over no matter what.
Rule 4: You gain EVs by defeating in-game Pokémon. Different Pokémon give different EVs.
Each Pokémon you battle in-game awards a different amount of EVs. For example, Patrat will award 1 Attack EV, while Blitzle will award 1 Speed EV.
This includes not just wild Pokémon battles, but Trainer Battles, Double Battles, Triple Battles, and Rotation Battles. In double, triple, and rotation battles, all Pokémon that participate in the battle will earn EVs.
Of course, there is an exception to this rule: your Pokémon do not earn EVs in battles where they would not gain experience. This includes battles against other players via local wireless, IR, or Wi-Fi, the battle against Reshiram (Black) or Zekrom (White) at N's Castle, and battles against NPCs in the Battle Subway or Battle Institute.
Rule 5: A Pokémon starts gaining EVs from its very first battle.
This is perhaps the very most important rule of all. For every battle that your Pokémon participates in and gains experience, it will earn EVs. This includes using an Exp. Share as well as switching out without attacking!
It's vitally important that you are ready for EV training before you begin exposing your Pokémon to combat.
EV Training Tools
The following is a compendium of the various tools available to trainers to ease the burden of EV training. Once you are finished training, it may be helpful to compare the stats against a damage calculator to check your work.
Macho Brace and Power Items
Pokemon White Map Guide
The Macho Brace doubles the EVs earned from battle at the cost of halving your Pokémon's Speed while equipped. For example, a Pokémon that normally awards 1 Speed EV will award 2 Speed EVs if your Pokémon holds a Macho Brace. You can get one from a man in a baseball uniform at the eastern gate in Nimbasa City that leads to Route 16.
The Power Items reward an additional 4 EVs to their corresponding stat after each battle your Pokémon participates in at the cost of halving your Pokémon's Speed while equipped. Each Power Item will reward the corresponding EVs regardless of what you earn otherwise. The Power Items can be purchased for 16 BP each at the Battle Subway. It is recommended that you purchase all six (costing a total of 96 BP for the entire set). The list of Power Items includes:
- Power Weight - 4 HP
- Power Bracer - 4 Attack
- Power Belt - 4 Defense
- Power Lens - 4 Special Attack
- Power Band - 4 Special Defense
- Power Anklet - 4 Speed
The Macho Brace and Power Items do not affect the number of EVs received from using Vitamins or Wings. The number of EVs gained for each item is set to 10 and 1, respectively.
Pokérus
A Pokémon that is infected by Pokérus or has been cured of Pokérus will earn double the EVs it normally would after a battle. This effect stacks with the boosts from Macho Brace and the Power Items. However, Pokérus does not double the EVs gained from Vitamins or Wings, which will be discussed later on.
It's recommended that you infect the Pokémon you want to EV train with Pokérus to save you a significant amount of time spent EV training. Pokérus is very rare, randomly appearing on one of your Pokémon after a battle. If you keep it in your party, it will eventually infect the other Pokémon. If the infected Pokémon is in your party for 1-4 days (A day corresponds to when the in-game clock rolls over to the next day. There is no way to tell exactly how long the infection will last.), it can no longer spread the virus to other Pokémon, but the doubling effect of Pokérus remains. Keeping the infected Pokémon in your box prevents it from wearing off, keeping the Pokémon 'contagious' for future EV training projects.
The fastest EV training is done with a combination of Pokérus and a Power Item, earning EVs at this rate per battle:
(y + 4) * 2
where y is the amount of EVs you would earn alone.
Vitamins
Vitamins will grant your Pokémon 10 EVs to the corresponding stat until your Pokémon reaches 100 EVs in that stat. If the Pokémon already had 100 or more EVs in the stat the Vitamin boosts, it will have no effect. You can buy all of the Vitamins at Shopping Mall Nine located on Route 9 for 9800. You can also buy them in the Battle Subway for 1 BP each, or in the Pokémon World Tournament in Black 2 and White 2. The six Vitamins available are as follows:
- HP Up - 10 HP EVs
- Protein - 10 Attack EVs
- Iron - 10 Defense EVs
- Calcium - 10 Special Attack EVs
- Zinc - 10 Special Defense EVs
- Carbos - 10 Speed EVs
EV Reducing Berries
The EV reducing berries are a set of berries introduced in Pokémon Emerald that reduce your Pokémon's EVs by 10 with every use and raise its happiness. The six berries cannot be obtained in-game in Black and White; they can only be be found in the Windswept Sky area in the Dream World. With the closure of the Dream World, the EV reducing berries are now unobtainable in Black and White unless you are able to trade locally with a Black 2 or White 2 game. Black 2 and White 2 have the luxury of making them purchasable on Route 5 or in the Join Avenue. The six berries include:
- Pomeg Berry - Removes 10 HP EVs
- Kelpsy Berry - Removes 10 Attack EVs
- Qualot Berry - Removes 10 Defense EVs
- Hondew Berry - Removes 10 Special Attack EVs
- Grepa Berry - Removes 10 Special Attack EVs
- Tamato Berry - Removes 10 Speed EVs
In fourth generation games, if your Pokémon had over 100 EVs already invested, consuming one of these berries would drop the value down to 100 EVs exactly. However, in the 5th generation, each EV reducing berry will only decrement the EV value by 10 regardless if it's over 100, restoring the third generation mechanic. For example, if your Pokémon has 200 EVs in its Attack stat and you use a Kelpsy Berry to lower it, the value will drop to 190. As a result, to completely wipe all the EVs from a stat that has the maximum number of EVs (255 EVs), you would need 26 EV reducing berries of the corresponding stat. Accumulating such a large number of berries is made even more tedious than past games due to the fact that there is no longer a way to grow them.
Because the berries are now difficult to obtain, it is recommended that you closely track your progress and save often when EV training. You may not have a way to reset the EVs if you make a mistake.
Fifth Generation Changes and Additions to the EV System
Application of EVs
Perhaps the biggest change in EV training since the entire EV system was changed with Gen 3 is a shift away from having to level up your Pokémon to view the effects of EVs.
After defeating a Pokémon and earning EVs, they are applied to your Pokémon's respective stat as soon as the battle ends or when said Pokémon levels up mid-battle. This means you can see the fruits of your labor immediately, without having to wait for your Pokémon to level up, and without having to resort to such things as the 'Box Trick'. Consequently, this means level 100 Pokémon can earn EVs through battle, as your Pokémon no longer needs to level up to reap the benefits of EVs. This development had the largest impact on Arceus, which can only be obtained at level 100 via events in both fourth and fifth generation games. Now, Arceus can be fully EVed in any stat instead of limiting itself to 100 EVs per stat from Vitamins.
Wings
The Wings are a set of items introduced in Pokémon Black and White that will grant your Pokémon 1 EV to the corresponding stat. They function similarly to the Vitamins, but can be used over the 100 EV limit set on Vitamins. In essence, you can completely EV train a Pokémon using Wings alone. Wings can be found in the shadowy patches that appear on Driftveil Drawbridge and Marvelous Bridge (along with wild Ducklett on Driftveil Drawbridge and Swanna on Marvelous Bridge). The six type of Wings are as follows:
- Health Wing - 1 HP EV
- Muscle Wing - 1 Attack EV
- Resist Wing - 1 Defense EV
- Genius Wing - 1 Special Attack EV
- Clever Wing - 1 Special Defense EV
- Swift Wing - 1 Speed EV
There is a seventh Wing that you can find on the bridges called the Pretty Wing, but it has no effect and only serves as an item to be sold. Additionally, the Ducklett on the Driftveil Drawbridge and the Swanna on the Marvelous Bridge that also appear in the shadow spots are good sources of HP and Speed EVs; Ducklett gives 1 HP EV and Swanna gives 2 Speed EVs. So, while you're out searching for Wings, you can start EV training your Pokémon on the bridge.
The EV Checker
You can no longer earn an Effort Ribbon for reaching 510 EVs. However, you can still check to see if you have properly EV trained your Pokémon by visiting the EV checker in Opelucid City in Black and White. They are located in the small house directly north of the Pokémon Center. The EV checker is the woman in white walking walking around the first floor.
When you speak to the EV checker, she will give you one of two messages. If the Pokémon at the head of your party has fewer than 510 EVs, then she will tell you 'Your … looks like it can try harder.' If it has 510 EVs, she will say 'Your … put in great effort!' You can conveniently use her to verify that you have properly EV trained your Pokémon. Here's how:
- Earn precisely 508 EVs (the effective maximum).
- Talk to her. She should say 'Your … looks like it can try a little harder.'
- Use one Wing of your choice.
- Talk to her. Her message should not have changed.
- Use one more Wing of your choice.
- Talk to her. Her message should now say 'Your … has put in a great effort!'
If you don't have two feathers to use, you can also earn exactly 2 EVs of your choice and talk to her to see if your message changes. If for some reason you receive the 'great effort' message before you expect to, then you have improperly EV trained, and you should probably reset and start over, or use EV reducing berries.
Similarly, calling Bianca on the Xtransceiver allows you to check the EVs on your Pokémon. She will say '…It seems like it can work a little harder. But I think it worked hard on its !' when a stat has at least 252 EVs but the Pokémon still has fewer than 510 EVs total. When the Pokémon has acquired all 510 EVs and has at least 252 EVs in a stat, she will say '…It has worked really hard, hasn't it? I think it worked hard particularly hard on its !'. If your Pokémon has 252 EVs in multiple stats, she will indicate all of them at once.
EV Training Hotspots
Although you can get EVs from Pokémon anywhere you want, there are certain ideal locations in-game where you can train your Pokémon in the fastest possible manner, and with the least effort.
Black and White
Pokémon | Levels | Location | Appearance Rate | EVs Given |
---|---|---|---|---|
HP | ||||
Stunfisk | 15-35 | Route 8 / Icirrus City (Surf) | 100% | 2 |
Victini | 15 | Liberty Island | 100%, only if Victini has not been captured and you have access to Liberty Gardens. | 3 |
Attack | ||||
Patrat / Lillipup | 2-4 | Route 1 | 50% / 50% | 1 / 1 |
Tranquill / Druddigon / Mienfoo | 31-33 | Dragonspiral Tower - Outside / Entrance (Single Grass) - Spring / Summer / Autumn | 30% / 30% / 30% | 2 / 2 / 1 |
Tranquill / Sawsbuck / Druddigon / Mienfoo | 34-37 | Dragonspiral Tower - Outside (Double Grass) - Spring / Summer / Autumn | 30% / 30% / 10% / 30% | 2 / 2 / 2 / 1 |
Sawsbuck / Beartic / Mienfoo | 30-33 | Dragonspiral Tower - Outside/Entrance (Double Grass) - Winter | 30% / 10% / 30% | 2 / 2 / 1 |
Druddigon / Golett / Mienfoo | 30-33 | Dragonspiral Tower - 1F | 30% / 50% / 20% | 2 / 1 / 1 |
Golett | 30-33 | Dragonspiral Tower - 2F | 100% | 1 |
Defense | ||||
Roggenrola | 10-13 | Wellspring Cave | 50% | 1 |
Sandslash / Cofagrigus / Onix | 47-50 | Relic Castle - B6F | 30% / 20% / 15% | 2 / 2 / 1 |
Sewaddle / Venipede | 14-17 | Pinwheel Forest (Inner area) | 35% / 15% | 1 / 1 |
Special Attack | ||||
Litwick | 26-29 | Celestial Tower - 2F | 100% | 1 |
Litwick / Elgyem | 26-29 | Celestial Tower - 3F to 5F | 85% (4F: 70%) (5F: 50%) / 15% (4F: 30%) (5F: 50%) | 1 / 1 |
Special Defense | ||||
Frillish | 5-15 | Route 4 / 17/ 18 / Driftveil City (Surf) | 100% | 1 |
Claydol | 47-50 | Relic Castle - Maze End (Volcarona's Chamber) | 100% | 2 |
Speed | ||||
Basculin | 5-15 | Route 1 / 3 / 6 / Striaton City (Surf) | 100% | 2 |
Black 2 and White 2
Pokémon | Levels | Location | Appearance Rate | EVs Given |
---|---|---|---|---|
HP | ||||
Grimer | 15-17 | Castelia Sewers (Surf) - Spring / Summer | 100% | 1 |
Stunfisk | 45-60 | Icirrus City (Surf) | 100% | 2 |
Audino | Various | Almost Everywhere - Shaking Grass | 2 | |
Attack | ||||
Sandile / Darumaka / Scraggy | 14-17 | Route 4 | 35% / 35% / 5% | 1 / 1 / 1 |
Mienshao / Druddigon / Golurk | 55-58 | Dragonspiral Tower - 1F | 20% / 30% / 50% | 2 / 2 / 2 |
Golurk | 55-58 | Dragonspiral Tower - 2F | 100% | 2 |
Banette / Golurk | 47-50 | Victory Road - Entrance | 70% / 30% | 2 / 2 |
Druddigon / Zweilous | 47-50 | Victory Road - Northeast Cave | 80% / 20% | 2 / 2 |
Patrat / Lillipup / Pidove / Riolu | 4-7 | Floccesy Ranch | 10% / 40% / 5% / 5% | 1 / 1 / 1 / 1 |
Patrat | 2-4 | Route 19 | 50% | 1 |
Defense | ||||
Sandshrew / Yamask | 18-21 | Relic Castle - 1F to B1F | 20% / 40% | 1 / 1 |
Nosepass / Ferroseed / Klink | 26-28 | Chargestone Cave - 1F | 10% / 20% / 24% (Increase all odds with Magnet Pull) | 1 / 1 / 1 |
Special Attack | ||||
Litwick | 27-30 | Celestial Tower - 1F | 100% | 1 |
Special Defense | ||||
Frillish | 7-15 | Virbank City (Surf) | 100% | 1 |
Baltoy | 27-30 | Relic Castle - Maze End (Volcarona's Chamber) | 100% | 1 |
Speed | ||||
Purrloin | 2-4 | Route 19 | 50% | 1 |
Basculin | 5-15 | Route 19 (Surf) | 100% | 2 |
Rattata / Zubat | 14-17 | Castelia Sewers | 45% / 45% | 1 / 1 |
EVing for Level 50
If you plan on battling on one of the lines in the Battle Subway or playing battles over local Wi-Fi, this section contains a few important exceptions you should be aware of before EVing your Pokémon. The following rules are here to guide you so that you don't waste EVs when you EV train your Pokémon for formats that use Flat Battle rules (All Pokémon have their levels reduced to 50).
First, the HP formula at level 50 simplifies to the following:
HP = (2 * BaseHP + IV + (EV / 4)) * Level / 100 + Level + 10
HP = (2 * BaseHP + IV + (EV / 4)) * 50/100 + 50 + 10
HP = (2 * BaseHP + IV + (EV / 4)) * 0.5 + 60
HP = BaseHP + 0.5 * IV + 0.125 * EV + 60
while the Stat formula at level 50 simplifies to the following:
Pokemon White Complete Guide List
Stat = ((2 * BaseStat + IV + (EV / 4)) * Level / 100 + 5) * Nature
Stat = ((2 * BaseStat + IV + (EV / 4)) * 50/100 + 5) * Nature
Stat = ((2 * BaseStat + IV + (EV / 4)) * 0.5 + 5) * Nature
Stat = (BaseStat + 0.5 * IV + 0.125 * EV + 5) * Nature
Essentially, it means that the effectiveness of IVs and EVs is halved, which brings us to the first rule:
Rule 1: Stat gains for EVs are halved.
Essentially, at level 50 it takes 8 EVs to equal one stat point. This statement may lead one to think that instead of having your EVs divided by 4 at all times, you should have your EVs divided by 8 at all times. Therefore, only 248 EVs would have to be invested to maximize a stat. That's not entirely true, though, as you'll see after reading the next rule.
Rule 2: IV/2 + EVs/8 must be a whole number.
If IV/2 + EV/8 is not a whole number, you have not invested enough EVs!
Alternatively, this rule can be written as 'IV + EV/4 must be an even number'.
Due to the way stats are calculated (after adding IV and EV gain, you round down), if your Pokémon has an odd IV (such as 31), then the total stat gain from EVs (that is, EV/4) should also be odd, so that they are divisible by two when combined. If your Pokémon's IV is even (such as 30), then the total EV gain (EV / 4) should also be even.
To show you what I'm talking about, let's take an example using Thundurus.
With a base 125 Special Attack, the stat formula at level 50 becomes:
Stat = (BaseStat + 0.5 * IV + 0.125 EV + 5) * Nature
Now, you would think that you would want your EVs to be 248 since it is divisible by 8, right? Let's plug in 125 for base Special Attack, 31 IV, and 248 EV (248 is divisible by 8), and see what we get:
Stat = (125 + 0.5 * 31 + 0.125 * 248 + 5) * Nature
Stat = (100 + 15.5 + 31 + 5) * Nature
Stat = (176.5) * Nature
Now, after rounding, we get 176*Nature. Essentially, we have not invested enough EVs into Special Attack to reach its maximum.
Lets bump our EVs up to 252.
Stat = (BaseStat + 0.5 * IV + 0.125 * EV + 5) * Nature
Stat = (125 + 0.5 * 31 + 0.125 * 252 + 5) * Nature
Stat = (125 + 15.5 + 31.5 + 5) * Nature
Stat = (177) * Nature
Because 152 is a whole number, no rounding is necessary, getting maximum effectiveness out of our EVs.
Now what do we do if our IV is 30 instead of 31? In that case, we should lower our EVs in the stat to only 248, so that we don't end up with a decimal point.
Stat = (BaseStat + 0.5 * 30 + 0.125 * 248 + 5) * Nature
Stat = (BaseStat + 15 + 31 + 5) * Nature
Since 15 and 31 both add up to a whole number (46), no EVs are wasted. Unfortunately, as expected, we can't reach Thundurus's maximum Special Attack with 30 IVs.