Contrary to some folks, I have seen and kept cories in groups of 1-4 and they have all thrived.

For a 10 gallon tank, I think a pair of cories is fine. If you add a school of 8 rasboras, and make sure your filtration is rated at least 20 gallons, and adding a couple live plants, and you should have a nice small tank.

Once every thing is established for a few months, you might be able to squeeze a few ghost shrimp, amano shrimp, or nerite snails in there for variety.