What kind of fish would go well in a 2 gallon tank?

Hello all. I have a two gallon hexagonal tank that is really itching for a/some resident/s. I used to have a Betta that died. right now it's a temporary home to some young tetra (two neon, one gold, and one black, when I upgrade the tank I'll get more of each) and 5 young ghost shrimp. But I want to know what to put in when they move out. I know Bettas are best, but I don't really want another one, and I am also trying to avoid the two guppies route. But what else is there? It is a two gallon tank with a bubbler stone and a bottom filter (not an electronic one) and those flat stone marbles (I can move to sand readily) and a plastic plant with frayed edges. I was thinking a drawf puffer, but I don't know how well it would do. What do you guys think?