Sure !
So you wanted to say something like:
"When I was 2, I loved my Pikachu and the Sky."
If so, then you were right in the gendering of Pikachu, as in French, saying "Ma Pikachu" totally is weird xD
"Quand j'avais 2 ans, j'aimais beaucoup mon Pikachu et le ciel."
"Mon" is masculine, and "Ma" is feminine, but in terms of grammar, masculine > feminine and in that case, since you say "Un Pokémon" and not "Une Pokémon" (which is feminine), you'd say "Mon Pikachu".
Am I clear enough ? I sometimes fail at explaining xD