Chansey!

Chansey is one of the most useful Pokemon you could have with you in Single battles. 

They have an incredibly high HP and good Special Defense Base Stat, which turn them into a Special Attack Wall.

Pokemon that rely on Special Attacks to take down their opponent will find a Chansey to be an Impenetrable wall.

Given that Chansey is so gifted with it's Special Defense, to make the Pokemon fair for the game, it's Defense stat is almost non-existent. How ever, this does not mean it cannot take a Physical hit! If you know how to train it right, it can at least take one strong Physical hit without feinting.

Lets take a look at Chansey's Base Stats so we know what we're dealing with.

250   HP

    5   Att

     5   Def

       35   Sp.Att

      105   Sp.Def

       50   Speed

For training Chansey, you want to get one with 31 IV in HP, Defense, and Special Defense. You also want to have one with a nature that adds 10% to the Defense stat, while taking from one of either Attack, Special Attack, or Speed stats. These natures are: Bold, Impish and Relaxed, in the same order.

When you have this Chansey, you want to train it so that it has 252 EVs in Defense, and 252 EVs in HP. This brings Chansey's Defense stat to a reasonable amount, and with such a bloated HP stat, it will definitely be able to hold it's own from a Physical hit.

Now, you may be asking, why didn't I say to do this with Blissey, given that Blissey has slightly more Base Stats than Chansey? Well, the answer is that Chansey, unlike Blissey, is able to use an item called an Eviolite. The Eviolite adds an extra 50% Defense and Special Defense to Pokemon holding it, if they have yet to evolve into their final form. This item makes Chansey much stronger than Blissey, and also really gives it that kick when it comes to being a Wall Pokemon.

All that sounds great, but a Wall Pokemon is nothing if it can't cause mayhem for the opponent along with standing in their way. So you're going to need a move set that can do this most of the time. Here is a move set that I think works best for this Chansey.

Soft Boiled (Level Up)

Toxic (TM)

Heal Bell (Egg Move)

Stealth Rock (Gen IV only)

This is a complicated Chansey to cook up. But it can be done, and as you can see, one attack only exists in Gen IV for this Pokemon, so all the cooking will have to be done in a Gen IV game with Stealth Rock TM.

To get the Egg Move Heal Bell, you'll need to breed a Male Skitty with around 31 IV in HP, Defense and Special Defense, and have it learn Heal Bell through leveling up. Use this Skitty to breed the move Heal Bell  and it's IVs across to a Chansey. When you have a Chansey with 31 IV in HP, Defense and Special Defense, you're set, kuz it'll also have Heal Bell. From there, just train its EVs as mentioned above, then level it up till it learns Soft Boiled, then Give it the TM for Toxic and Stealth Rock. From there, you can send it over to your Generation V game through the Transfer machine.

Once in Pokemon Black or White, give it the Eviolite, and you're ready to use it in Battle. (Given it is at least level 50)
The idea for using this Pokemon is to have it use Stealth rock at the start, if you're opponent has sent out a non-steel type Pokemon or a Pokemon that doesn't have Poison Heal Ability, then the next attack would be Toxic, and from there, you would alternate between Softboil when needed, keep in mind, you might have to anticipate an attack and heal directly after it in the same turn to keep Chansey from feinting, (If trick room is in play, then Chansey should be able to heal before they strike) and as time goes on, Toxic will take them down eventually. It's also good to have a Ghost type Pokemon of some sort in the team, so when you can see the opponent is about to use a Fighting attack on Chansey, you can swap to that Pokemon, without causing it damage (Assuming there isn't a Stealth Rock in play on your field or anything similar)

I hope you find this information useful, enjoy playing with you pinkolicious Chansey! Stay tuned for more useful information.