I've long been of the opinion that Sora would make a good pony. Yours just convinces me further with his eager-puppy friendly dorkiness and relentless optimism. It's like Riku said in 3D, it's hard not to smile around him.

And Karkat... I've not interacted with him mostly because I imagine he'd drive Twilight nuts (which isn't entirely a bad thing but would mostly just lead to her giving up and shutting the gear off on him) but that doesn't mean I haven't stalked plenty of his threads and been quite impressed by how... balanced he is in your hands. You've got the thoughtful leader side, the cranky asshole side, the doofy romantic comedy lover side, and more, all rolled into one and I really think you pull it off quite well! Kudos.