Lots of good times playing this game, in my opinion it's the last final Fantasy worth playing.
Kimahri- he was a tough one to pair but given the Ronso's affinity for horns I figured Rhyhorn would do.
Tidus- sad thing is he's even more annoying than Psyduck
Yuna- Another tough one, I was trying to think of a pokemon that reminded me of Valefor (Yuna's first summon) so I was considering Pigeot but ultimately I wanted Lugia because he felt a bit more in line with her significance as a character and his head actually does look a tiny bit like Valefor, though admittedly it's a stretch.
Wakka- Initially I gave him Squirtle but Staryu actually reminds me a bit of a blitzball, I could see him tossing the thing around like a Frisbee.
Lulu- Being that she is the personification of "cool" I had to give her a bunch of badass psychic/dark types.
Rikku- Went with Magneton to allude to her Al Bhed heritage and their affinity for machina. Porygon could have worked too as that's actually a man-made pokemon.
Auron- he's dead so that was an easy one. I liked the idea of ghastly because it's ghostly trails look a bit like the pyreflies that emanate from a person when they're sent to the farplane.