Balas get HUGE, like, REALLY huge...and are schoolers I believe....which means your looking at a gigantic tank to house them properly....and I'd imagine they'd kill a betta rather quickly.
Tank mates depend on a couple factors: Tank size and Betta temperament.
Some bettas are better off alone and hate tank mates, others don't mind company.
What you can put with them all depends on tank size, though if you want actual FISH as tank-mates you'll want a 10+ gallon. 5 gallons is the smallest tank size you can get away with having tank mates in, but your options are limited to shrimp, ADFs, and snails.