nothing from the sounds of it, he's being your average betta. Looking at your stocking list i'm not surprised he's chasing the other fish. bettas often don't distinguish colorful fish from other male bettas, especially those like guppies that have showy tails. [edit] also bettas and gouramis are from the same family (anabantoids) and it is very likely that they will fight constantly over territory as they will all occupy the same space.
Unless you want to start losing fish, you really need to give the betta his own place. meaning either his own small tank, or a divided section of the one he is in.
as one other sidenote, you should rehome those crabs to. besides there being no fully aquatic freshwater crabs, meaning you would have to proved a place where they can surface (which is more or less easy to remedy) they WILL eat your fish if given the chance. The folks over in the freshwater invertebrate section would know more though.