Before we begin:
leviosa8 posted a
sweet pic from a RyoKai dj.
In the last week, I've seen two MomoKai stories that used "taller boy" and "shorter boy" to differentiate between the characters. Only they didn't agree about which was which.
This sort of thing might work for Hagrid/Dobby fic, but Momo and Kaidoh are too close in height. (I think Kaidoh is the technically taller, but Momo's hair sticks up pretty high.)
Here are few epithets you can use instead. It's clip-n-save!
Momo Kaidoh
purple-eyed boy dark-eyed boy
spikey-haired boy bandana boy
Dunk Smash Specialist Boomerang Snake Expert
easy-going boy uptight boy
hamburger addict training freak
boy with the annoying voice boy with the sexy voice
Or you could just use their names.