updated to reflect this trick's applicability in gen 3.
Usually, a Pokémon's stats are calculated upon leveling up; however, Pokémon stored in the [[PC]] have only the numbers used in the calculations stored (namely the [[Effort values|EVs]], [[Individual values|IVs]] and [[base stats]]), so depositing and withdrawing a Pokémon from the PC will cause its stats to be recalculated. This method can be used to EV train level 100 Pokémon by using [[vitamin]]s.
III]] onward, the trick is obsolete. In these games, effort values are immediately applied to stats as soon as a Pokémon's effort values are modified.