You mean move Move Maniac,In FireRed and LeafGreen.
Move Maniac
>A man on Two Island also allows the player to have a Pokémon relearn a move. The price is different from Ruby, Sapphire and Emerald, however. Instead of a Heart Scale, either two TinyMushrooms or one Big Mushroom must be given. This is likely due to Luvdisc not being native to the Kanto and Sevii Islands regions, while Paras and Parasect are.
He is located
>Next to his house is a small Game Corner that allows players to compete using their Pokémon in wireless minigames with another FireRed, LeafGreen, or Emerald game.
Source
I love Weird things ¯(°_o)/¯
