Mollys can breed with any other type of molly fish
Mollies can get gravid at a few weeks old.
I guess its about as possible as a small monkey trying to mate with a gorilla. On paper, in theory, they can probably do it but in practice the chances are very small that they would succeed and its even less likely that any offspring will eventuate.
yes all fish mate
They are of the same species so yes they can mate.
Obviously one male and one female is needed, but also the temperature of your water must be warm enough as we are talking about tropical fish. Different types of molly can breed, so can different species from their family. Guppy/molly hybrids (gullies) are an example.
no. fish can only mate with fish of the same species. Gouramis mate with gouramis and platys mate with platys.
never because everyone called molly is a loner
Do you mean will they mate with other fish or get along with other fish? They will not mate with other fish, but they will get along without tetras.
To mate fish, you should see how the fish you want to mate, mate. Then you should put them in the same tank and watch them. I'm not an expert so search the web for a more through answer.
of course, why not?
No.
Goldfish are cold water fish and should not be kept in an aquarium with a tropical molly. There is no way they can cross breed. Fish are not stupid and do know the difference between one of their own species and a species that should not be in there with them. It is quite possible the goldfish will eventually kill the molly. Failing that, if your tank is not heated, the Molly will probably die during the winter if the temperature gets below 65F for too long anyway.