I own, Red, Yellow, Gold, Crystal, Ruby, Fire red, Stadiums 1 & 2, Pokemon Snap, Pokemon Dash, Pokemon Colosseum. So that's 11.
But in my whole house we have R/B/Y, G/S/C, R/S, FR/LG, and then the latter ones that I mentioned above. So that would make 15! But yeah, the ones that I don't specifically own belong to my sister.