Lol wow.... Well the pet store here, the owner of the store has bettas in with blind cave tetras (wonderful), danios (pretty good), the mellow with guppies (occasional nipped fin but nothing drastic), neon tetras (very good).... The girl tosses them willy nilly into wherever she thinks they'll fit. Rosy barbs. Cichlids. Gouramis. Grumpy betta with guppies. A-should-be-alone betta with a slow critter (like snails and plecos). Betta with glass and ghost shrimp, no plants.
Breed for the breed, not for the money; the words any REAL breeder would understand.
You must know nothing in order to know all, for all is nothing and nothing is for all.