Emerald cories aren't cories, they are bronchis splendens, not related to corydoras aenus (bronze/albino), bronze/albino get pretty big (the largest actually) so a 20 gallon is reccomended. Peppereds and Pandas'd be fine in a 10 though. Cories need a shoal of 4 as others have said. Don't get 2 and get more later. Might as well just get them all at once.
In order of largest to smallest:
-Bronze/Albino (20 gallon is better)
-Peppered/Panda (fine in a 10)
-Hasborus/Pygmy (fine in a 10)
You could fit probably 4-5 of the peppered/panda in a 10 and 6 of the hasborus/pygmy. Pandas aren't has hardy. For some reason they don't last as long!!
10 Gallon Tank:
~Countless Pond Snails~1 Espe's Rasbora~1 Harlequin Rasbora~ 5 and 5.5 Gallon Tanks:
Avatar by Fenghuang
Many of my scaly friends from my original tank from 2011 have passed, except for two! I am in the process of re-doing my tank. :)