I have had community tanks most of my life and guppies get along with other mild mannered fish. Mollies, Platys, Neon Tetras, Cory Catfish (scavengers). I would avoid swordtails as they can be aggressive. You can do your own research by doing a search on Community tanks. Also, while some people insist Betta fish cannot be kept in a community tank, I have had one in every tank I have ever kept, usually with no issues, other than the fact that it may eat the fry of the live bearers. But with guppies, you need to have 2-3 females for each male. They are prolific breeders and if you have too many males, they will literally try to breed with the females until they die. Neon tetras do best in schools of 6 or more. Platys and Mollies can get by in pairs or several.