Question time!

Is it okay for us to draw other people's Pokemon in the Sketchbook? Now that I think about it, drawing Ouroboros taking a bite out of that Tyrantrum's tail would have been a great moment to capture in art, but Ouroboros belongs to Gemma's character, Callie. I'm just wondering because if another moment like that comes up again in the future where someone else's Pokemon does something great and memorable but another person wants to do the art for it, would this kind of thing be permitted?

I'm just asking because the rules in the Sketchbook say our own Pokemon, but I'm not sure if it took instances like this into account.