I didn't notice you mention gender, can you reply with that please? Mollies and Platys are usually nice community fish, but if they're kept in a "Male:Female" ratio of less than 1:2, the males will become extremely aggressive (usually toward other males, but they could take it out on the tetras). Females on the other hand tend to remain relative peaceful if they're kept in an all-female group.
You can tell a female molly from a male molly like this:
Look at the anal fin (the single fin on the bottom rear of the fish)
-- A female's anal fin will look just like a regular fin.
-- A male's anal fin will be curled up into something called a "gonopodium", it's what they use to fertilize the females.
As far as deliberately trying to eat the Neons - I find that highly unlikely unless you're feeding them nothing but vegetables. Mollies are algae-eaters in nature and vegetarians in the aquarium, but they do need a little protein every so often.
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