Just played around with team for 2-3 minutes or so and came up with this. It's a fully free to play team and manages a 6 combo started by main and a 5 combo started by various other means. Not an amazing team, but something to start with and or aim for.

I do advise trying to learn the game mechanics yourself however so you can crunch characters on your own. Team building is actually one of the fun aspects of this game!