Megumi Hayashibara, Musashi I Miki Shinichirou, Kojiro I Rachael Lillis, Jessie I
Eric Stuart, James I Addie Blaustein, Meowth

Megumi Hayashibara

Main Role: Musashi

Other Roles in Pokemon: Fushigidane (Bulbasaur), Pigeon (Pidgeotto)

Other Anime Roles: Ranma Saotome Female ("Ranma 1/2"), Lina Inverse ("Slayers"),
Rei Aiyanami ("Evangelion"), Pai ("3x3 Eyes"), Achika ("Tenchi Muyo in Love"),
Amano Ai ("Video Girl Ai"), among many, many others.

Born March 30th, 1967, in Tokyo, Megumi Hayashibara is currently the most famous female seiyuu in Japan.
She made her debut in 1986 as the kindergartner in the first episode of "Maison Ikkoku".
She has a few CDs out, and she's also made many appearences on covers
of magazines and radio shows. You can hear Megumi in the
English version of Pokemon as Pidgeotto.

Listen to Megumi as Musashi
Listen to Megumi as Ranma Saotome

Miki Shinichirou

Main Role: Kojiro

Other Roles in Pokemon: Pokemon Zukan (Dexter), Hitodeman (Staryu),
Lizardon (Charizard)

Other Anime Roles: Yuuki Keisuke ("Fushigi Yuugi"), Tsurugi Hikaru
("Key the Metal Idol"), Larva ("Vampire Princess Miyu)

Uh...I don't really know much about Michi yet...Sorry ^_^;...I do know
that he's in a Japanese band called Weiss, and also that you can hear
him in the English version of Pokemon as Staryu.
He's the person that goes "Hyah!" :).

Listen to Michi as Kojiro

Main Role: Jessie

Other Roles on Pokemon: Jessie Belle, Misty, Melanie, Jigglypuff, Vulpix, Chansey, Ditto, Goldeen, Venonat, and she did Pikachu in a couple of episodes...

Other Anime Roles: Utena ("Revolutionary Girl Utena")

Rachel could probably be considered the goddess of Pokemon voice-acting ^_^. As you can see, Rachel, a New York city resident, has done many voices in the show.

Listen to Rachel as Jessie
Listen Rachel as Misty

Main Role: James

Other Roles in Pokemon: Brock, Lt. Surge, Squirtle, Dexter, Aerodactyl, Charizard

Other Anime Roles: Gourry Gabriev ("Slayers")

Eric Stuart was born in 1968 in Brooklyn. He is the lead singer of a four-man band that has toured with legendary artists such as Chicago and Ringo Starr. Eric wasn't James' voice actor until around episode ten...I believe that before then, he was dubbed by Ted Lewis. I defintely prefer Eric, though. ^_^

Listen to Eric as James
Listen to Eric as Brock
Listen to Eric as Gourry Gabriev

Addie Blaustein

Main Role: Meowth

Other Roles in Pokemon: Hippie ("Wake Up, Snorlax!"), Growlithe

I know very, very little about Addie, except for the fact that he didn't always play Meowth. There was another voice actor that he replaced about halfway through the currently dubbed episodes.

Listen to Addie as Meowth
Listen to Addie as the Hippie