Corys will be better in more numbers. The more the better. 6 minimum, preferably 8.
Saying that, you havent said what your other stocking is. Increasing the numbers might lead to overstocking of a 10g tank. If you want to keep your cory happy in a community tank, i would recommend a bigger tank.
Corys wont be aggresive to newcomers. I have 2 tiny panda corys, smaller than they sell in the store and they swim around fine with the others.