A big part of Pokemon battles is planning Pokemon's moves and their Nature. Pokemon Brilliant Diamond and Shining Pearl allow players to increase their Pokemon's EVs, making them stronger, faster, or more defensive than they normally would be, and things like breeding make for great tools to do this and look for a Pokemon's best Nature and traits simultaneously. Another thing to consider is that some Pokemon come with different abilities that impact their performance in many ways both in battle and outside of it.