Mollies produce a lot of ammonia so they aren't really reccommended for a 10 gallon.... that and they can actually get really aggressive
You could do 5 neon tetras (though I hear they can be a bit harder to care for as they are delicate)
or about 5 rasboras or platies <---- both are really hardy
6 pygmy corries or 4 regular ones (they are actually a LOT of fun to have and I have noticed that even more aggressive bettas ignore them pretty well)
but sadly, not all male bettas are cut out for community life, the best bet would to buy one or two dividers and divide your tank in half or in threes... then you can have 3 males... and ghost shrimp are ALWAYS an easy and cheap way to add a clean up crew... and they have almost a ZERO bioload <--- I love the little boogers