In Pokemon Ruby, I gave flight to Skarmory. She's a large pokemon, a steel type and built like a 747, so it was plausible she could carry me on her back.

In Pearl, I was grooming over my water starter, Pipilup, to be my flight pokemon. Then he had to go and evolve into Emporeon, a flightless penguin. Last night, when I earned Fly, the only levelled-up Pokemon I had that could learn it was... Zubat? Leaving me with this image of tossing a tiny Zubat into the air and holding onto him for 100 miles.

(Poor Kadabra. The only thing Emporeon has to hold on with is triplets of spikes on his wings!)