From Bulbapedia, the community-driven Pokémon encyclopedia.
Michael Haigney was a voice actor, voice director and English-language adaptation writer under 4Kids Entertainment for its dub of the Pokémon anime.
Haigney was the original voice director on Pokémon, and was also one of the original voice actors, originally providing fill-in voices for Pokémon that had not been cast. During the sixth season, Haigney left the series. After his departure, stock footage was used to voice Ash's Snorlax in Wheel Of Frontier, as well as Brock's Geodude in Grating Spaces!.
In the Pokémon 4Ever DVD commentary, Haigney explains that he didn't realize Charmander would become a major character, believing it to only be a character of the day.
Voices on Pokémon