Each type of Pokémon will give your Pokémon different EV points when they battle. Know which Pokémon give which EV points and only fight if those are EV points that you want.
For example, fighting a Nidoqueen gives 3 EV points to HP, while fighting a Machamp gives 3 EV points to Attack. Keep in mind, however, that while some Pokémon may give a high number of EV points in a particular stat, those Pokémon may be hard to find. You may be better off fighting Pokémon which are easy to encounter but still give at least a point or two in the stat (or stats) you want.
You can buy Vitamins from Shopping Mall 9 in Black and White.
Find out if your Pokémon has Pokérus by checking their status effects. You’ll also be told by the nurse at a Pokémon Center if your Pokémon has Pokérus. Keep in mind that this virus is very rare. You may never encounter it.
The major downside it that the wings only increase 1 stat and which wing you find is random. It is also time consuming to find the wings.
