Serebii EV training is an in-depth technique documented on the Serebii.net website that offers Pokémon trainers a way to maximize the stat increases a Pokémon receives when it levels. However, it is a lengthy process and aimed more directly at advanced trainers.
EV stands for "Effort Value" and is a value given to a Pokémon to determine what stats increase when it gains a level. They are gained from battling Pokémon who give the player experience. Each Pokémon has a different EV award and it takes four of them for a stat to increase one point. This technique involves fighting Pokémon that have an EV for the stat the player wishes to increase to maximize the power of the player's Pokémon when it levels.