Note: you may be looking for Agitha from The Legend of Zelda: Twilight Princess.
Agatha is a character in the Pokémon series of games that first debuted in the Generation I games. She later appeared in the Generation III games with the release of Pokémon FireRed and LeafGreen. In the games, she is the third member of the Elite Four group where she uses ghost type Pokémon (among others such as Golbat and Arbok that are similar in appearance). She also appears in the Nintendo 64 video game Pokémon Stadium where you'll have to fight her twice. As you can obviously see by her appearance, she is an old woman that needs a cane to get around.