It's the same thing for a tank, only it's way easier.Fair warning, I am a noob at actual tanks. A bowl I can do, that's easy. Add a heater and replace the water weekly. Tadaaa happy heathy betta. Tanks are new for me, and seem to have more to worry about.
What do you think? If I return all three I guess I will try platy or tetra unless someone has a better suggestion. Any ideas? Are mollies often little buttheads?
The problem is your choice of stock. Mollies need a much bigger tank and are not a good choice to go with a betta. I would return all of them, and see about getting a group of SMALL peaceful fish, like tetras or rasboras. That's what's worked for me.
HahahaThe betta forum will no doubt offer better advice than I have