Fenrir (VP1) vs. Belial (WA4)
Heavy:
Levin Brenton (WAXF) vs. Edgar Roni Figaro (FF6)
MBlock / Evade is not Levin's friend.
Middle:
Tony (WA4) vs. Byleth Eisner (FE3H)
Tony doubles with his basic attack, but I'm inclined to respect-check him here. Maybe he barely 4HKOs but if he ever misses or Crest of Flames ever triggers or if Byleth gets a crit on SotC counters, Tony is toast (either immediately or once Byleth gets a turn). For that matter, since Byleth is getting doubled anyway, the goofy White Magic setup with WM Avo +20 and Nosferatu also serve the cause of just ensuring Byleth gets one turn with which to Sublime Heaven and blow Tony up with.
Light:
Heather (FE10) vs. Karn (BoF1)
Traditionally, having counterattacks is a huge swing in Light slugfests. And I don't think I'd let Karn double, Heather is pretty blazingly fast (even if Karn is too, but in a system where this is less meaningful).