Mollies actually grow too large and have a heavy bio-load so are not suitable for a 10g. Guppy males are fine, plus you get more color and no fry to deal with. Many say neons need a larger tank but IMO a 10g is fine. I have 11 in a 12g tank with a betta, and 5 male Endlers. Most cory's get too large for a 10g. You can look into dwarf or pygmy cories or perhaps Panda's or even Peppered which are both smaller species. Aspidoras are great if you can find them. They are in the cory family. So if you keep the molly's, which I don't advise, your tank stock is full. If you'd rehome the Molly's the upping your neon count, adding some guppies, and 3 cory's would work fine.
