I personally think Steven Blum would be a great Dalton or Magus. David Kaye could work for the other one.
Whenever I think of Queen Zeal, I personally think of Ursula from the Little Mermaid voice-wise. Wendee Lee is an awesome choice as well.
Mute Bob would have to be my pick for Crono what with him being mute and all.
Caitlin Glass would be a decent Lucca.
Steven Kramer, Mike McFarland, Michael Dobson for Gaspar, Melchior and Belthasar respectively.
I honestly don't follow female VA's enough to put in my opinion on Ayla or Marle. Kelly Sheridan or Tara Strong could do either of them though, along with Crono's Mom.
Steven Kramer could double as Taban, he is pretty versatile.
Frog's difficult to pick because who knows if they'd go with Middle English Frog or Japanese Frog. I think Richard Ian Cox would be for Japanese Frog, Ted Cole for the Middle English one.
Robo....Rick Astley! Ok, dumb joke. I honestly liked J's tongue-in-cheek suggestion of James Earl Jones.
Brad Swaile has the squeakiness to do the Chancellor. If he could pull off an old man's voice he'd be perfect. Don Brown could do it no problem though.
Vic Mignogna as Johnny, and whatever the opening song is, Vic Mignogna should sing it.
Todd Haberkorn and Greg Ayers would make a good Masa and Mune.
Lex Lang for the Nu.
Brad Swaile again for Spekkio.
Richard Ian Cox could do a good Toma and Ozzie, Kirby Morrow for Slash and as I said before, I don't follow female VA's enough to judge on Flea.
Too many characters to keep up with, I'm dizzy just thinking about it.
You know what? Just put Vic Mignogna, Steven Blum and Tara Strong for the rest of them. They have enough talent between the three of them to take care of the rest.