You need at least a 10 gallon to house anything more. A five gallon is good for a betta and shrimp, or betta and snail (zebra, horned, apple, onion)
I have had my bettas without problems with many fish, including platys, danios, tetras of sorts, mollies (regular and balloon), guppies and others... I introduce the betta to the fish - not the other way around. this way it is not his territory
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.