Who will play him in KH3 now?
Genie was voiced by Dan Castellaneta (Homer Simpson). Castellaneta also voiced Genie in the 2nd movie and the TV series.
James Woods played Hades in every KH game that had Hades. IIRC, Woods also plays the games.
Jim Meskimen then replaced Castellaneta a few years back. We first heard him as the Kingdom Hearts Genie in 2.5's Re:Coded movie (they re-used Castellanetta's recordings for previous games in the HD rereleases).