Old Avengers vs New Avengers
Old Avengers:
1. Ironman
2. Warmachine
3. Hulk
4. Thor
5. Captain America
6. Bucky
7. Black Widow
8. Hawkeye
New Avengers:
1. Vision
2. Scarlet Witch
3. Quicksilver
4. Antman
5. Falcon
6. Spiderman
7. Black Panther
8. Sharon Carter
Everyone is in standard gear, fight in an abandoned airport. Characters are not bloodlusted but are completely willing to kill their opponents (just like Cap has no qualms about knifing an enemy soldier in the back). Everybody gets earpieces so they can communicate with their team during the fight.
Round 1: teams know nothing about each other. Random encounter.
Round 2: teams know about the strengths/weaknesses/powers of everyone and get 30 mins. strategy time before the fight.
P.S.- if you're wondering how I divided between old and new members, old Avenger is any hero who made an appearance before the first Avengers movie, a new avenger is a hero who only appeared after the first Avenger movie. I didn't include Dr. Strange because he has not interacted with any of the other Avengers yet (other than a post credit scene).