Hmm, I'll throw some around for Cloud/Cid/etc.
- charging limit up (or a certain number of units) in a single battle triggers something, like hp/mp recovery for the character or allies
- combat resistance to slash, hit, and/or shoot if defending in the front row (good panic button or front tank for bruiser/counter build)
- first time revived in combat, gain haste/regen
- combat critical bonus, like improving crit rate of allies in front row (lol if Cid had this)
- while all allies are alive, benefit from a level bonus (might screw up or help things like Goblin Punch)
- 1x mega-all
For Vincent, Cid's and Cait Sith's current passive would work. You could also try a combat bonus to physical and/or magical evasion after attacking, though that may overlap a little with Yuffie.