In GSC, the first time you use a Pokémon Center when one of your Pokémon has caught Pokérus, the nurse mentions "tiny life forms", and then Prof. Elm calls you about it. However, he says "it doesn't seem to do anything". This is incorrect; Pokérus doubles the rate of EV gain, similar to a Macho Brace. He should mention something about "effort", since that's how EVs are referred to in-game.
In GSC, the first time you use a Pokémon Center when one of your Pokémon has caught Pokérus, the nurse mentions "tiny life forms", and then Prof. Elm calls you about it. However, he says "it doesn't seem to do anything". This is incorrect; Pokérus doubles the rate of EV gain, similar to a Macho Brace. He should mention something about "effort", since that's how EVs are referred to in-game.