Can bettas an guppys breed togather?

Bettas and guppies are two different species and cannot breed together. They belong to two different families of fish, with bettas belonging to the Osphronemidae family and guppies belonging to the Poeciliidae family.

How do you tell how many babies your guppy is going to have?
Is it normal for my dalmatian molly to be chasing in 20 gallon tank aggresively after just introduced the are young still and as they grow I am moving them a new tank?