2 dwarf gouramis is a definite no - 2 of them need more space than a 10, and since only males are sold at LFS (females are only gray colored) and males tend to be aggressive to one another even in larger setups, it's not a good idea. A male and a female molly wouldn't kill each other, but you might end up with a whole bunch of baby mollies...I'm sure someone else can give you more advice about them though, I'm not a molly fan.