All over WoW you can battle various wild pets and you can potentially capture them. They have all different levels depending on where you're battling them (higher level zones tend to have higher level pets).
For the Tournament of Celestials, you need to have 15 pets levelled to 25, that you "levelled yourself".
What counts as levelling them myself? Taking them from 1-25? Or can I encounter a level, say, 23 pet in the wild, level it 2 more levels, and that's countable?