I'mma add to Kidd Pirates vs Red Hair Pirates:
- Payback war
- Rocky Port incident, we're gonna see this
- Whitebeard Pirates vs Big Mom Pirates, since Perospero hinted at them having battles in the past
- Whitebeard vs Crocodile
- Magellan vs Shiryu, I doubt Shiryu just costituited himself
- Doflamingo vs Crocodile, if a fight really happened. What we saw was just a skirmish.