Anything under a 5 gallon is to unstable, You might get a cycle and have it go fine for some time and then boom you loose it,,
I get that all the time with my 3 gallons, Be good for a month, Then it just looses it,
Always in NEED & looking for more Tanks!
Mollies could pose a risk for the betta. I tried to keep mollies with angelfish and discus but they began nipping at both the angelfish and the discus fins. While betta could possibly hold off these attacks should they occur,,it would no doubt stress the betta.
The most important medication in your fish medicine cabinet is.. Clean water.