Just for the record, I am not trying to bug you. I am trying to help you get a tank that will work for the fish, and for you. You came onto a fish board, so obviously you are going to be advised about what is best for the fish. Most people on here will probably tell you that Mollies will not be happy, full grown, in a 10 gallon. Especially with all those other fish.
Also, Be careful with your Otos...they are very sensitive to water conditions, and to keep good water conditions in that tank with all those fish, you will need to do water changes frequently.
Since you do use the inch per gallon rule (Usually), it doesn't even work out that way.
Mollies = 8"
Female Bettas = 8"
Otos = 3"
19".
Again, I am NOT picking on you. I am trying to help you do what is going be best for your fish.
Edit: I would see no problem with just the female Bettas and Otos in that tank. It's the Mollies that are the problem. They are going to get pretty big, and they are not a slim 4" either...