Effort Values (EVs) are hidden values in the core Pokémon games that determine the growth of your Pokémon's stats. Unlike base stats (which are specific to a species) or Individual Values (IVs, which are essentially the Pokémon's genetics), EVs represent the "effort" or training a Pokémon puts in.
Every time you defeat a Pokémon, your Pokémon gains EVs based on the species defeated. For example, defeating a Geodude yields Defense EVs, while defeating a Zubat yields Speed EVs.
A Pokémon can have a maximum of 510 total EVs, with a maximum of 255 in any single stat. Importantly, at level 100, every 4 EVs in a specific stat equates to 1 additional stat point. This means a fully EV-trained Pokémon can have up to 63 extra points in a stat compared to an untrained one!
The LeafGreen & FireRed EV Helper is an open-source tool designed to help you quickly figure out exactly which Pokémon you need to defeat to optimally train your teams in Generation 3 games without needing out-of-date text guides.
Data provided by PokéAPI.
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