Best type is what your style is. Its nice to use the Holon Energy Types, IE Grass Electric, WP, FF etc. or just Play what the most popular deck's weakness' are.
I was in line to play the Japanese Nat'l Champ, but they closed up the Main Gaming room @ 8pm sharp. Yamato and the Japanese Champ where offering games and Legend Maker and POP4 Packs to those who waited in line to play them. I'll try again tomorrow.
Hawaii 2007 Worlds.
Mabey something with Mew ex as a starter, Holon Transiever for mentor and build the monster on the bench, then have Mew copy the attack, or power move to escape.