Summons in general lore is never consistent, which was always strange to me. It is strange how Leviathan is female in some games, but male in others. I always thought Phoenix was a female, FFXI confirmed that only for him to be a "Guy..." in XIV....... Eh........I always liked Shiva and the others who were always consistent. It gave them character.
Yoshi as a Primal does not really make sense, but history says it does not have to make sense lol. So, I agree with the OP.
