Since he often uses MP Busters to counter magic, I went with a purely physical team. Crono offers great offensive magic and good physical attacks, so he's really the best of both worlds. I used him, Ayla, and Robo.
Use Crono's Luminare while you have MP. Then you can switch to physical attacks.
Robo's Apocalypse Arm equipped with the Dragon's Tear came it handy here. Every attack had a 30% chance of dealing 9999 damage which was nice. Also his Heal Beam could come in handy to keep your party's HP in the 900s. (DD has a powerful attack that can take 700+ worth of damage.)
You can start Ayla off with her most powerful techs (doubles and even the triples), but beware of the MP buster counter.
If you have a lot of ethers and prefer using magic, I'd swap Ayla with Lucca. Her Flare works just as well as Luminare. When the party is low on MP have her use Ethers and Elixirs.