DON'T GET FEMALES!!!
The male will kill the females, you can't keep them together all the time. Only when they are going to breed and I don't even know how to do that.
You could try getting only females, Depending on the tank size. Really if you only getting a 5 gallon then you should just get a single male. If he isn't to aggressive (Some bettas are) Then you could keep an African Dwarf frog with him, or an apple snail, maybe some ghost shrimp.
And just before you laid dead weight upon its shores, I stung you in the face for that's the nature of my core.