Apollo has a Fearow and a Golurk, both of whom are larger than average, so carrying capacity isn't an issue for him. Especially since not only is he not very tall, but under that cloak and loose clothing he's so skinny you can see his ribs.

Which reminds me; his Archen is going to be evolving early this week, so he'll go from having a vicious and territorial rock bird to a vicious and territorial rock bird that can fly. He won't even be trying to ride her anytime soon.