In a 10g, I would guess probably just bottom dwellers will work as there's not a ton of room. If you add lots of floating plants, maybe things will work better, but even so, there just isn't much room for something big enough to not get eaten...even if it's fast, not much place to hide.
I keep my betta by himself in a 5g Fluval Chi. There used to be a red cherry shrimp or two in there also but I think they got eaten.
In my 20g hex, I have a pair of paradise fish (very similar disposition to a betta) that stick near the top and a small breeding pair of kribensis in the bottom. There is some chasing, especially right now with the kribs watching their eggs, but so far it's working out. I also have quite a lot of guppy/najas gras in there. But that's something like 18-20" high vs. the 12" height of a 10g.