Two cories are your safest bet
Bala sharks are not appropriate for such a small tank. They can grow to be a good 14" and because they are such a nervous, skiddish fish, they'll constantly be bashing their faces in as they dart around your tank. Not a happy thing to do to fishies.
Mollies are brackish water fish and will also not be happy in your tank without a heeping amount of salt, which would kill off your neons for sure, and probably irritate your other fish.
One dwarf gourami might do well in your tank. Two males will constantly fight, and even a male/female pair (provided you can find a female, they're not common in the market because they aren't as pretty as the males) may also chase each other around quite a bit. A single male, if you find one small enough, might not have the dominace developed yet to become an aggressive bully and could possibly be raised with your fish.
But cories would be the most peaceful and best additions to your tank.
~~Colesea