Tony Stark (Iron Man): Volleyball

Steve Rogers (Captain America): Soccer

Bruce Banner (Hulk): Basketball

Clint Barton (Hawkeye): Tennis

Thor Odinson: Baseball

Pietro Maximoff (Quicksilver): Skateboarding

Natasha Romanoff (Black Widow): Figure Skating

Wanda Maximoff (Scarlet Witch): Ballet

Helen Cho: Do academics count?

Wade Wilson (Deadpool): BMX

James Howlett\Logan (Wolverine): Hockey

Scott Summers (Cyclops): Karate

Alexander Summers (Havok): Fencing

Jean Grey: Horse Racing

Ororo Munroe (Storm): Roller Derby

Peter Parker (Spider-Man): Competitive Dance

Susan Storm (Invisible Woman): Volleyball

Reed Richards (Mr.Fantastic): Track

Jonathan Storm (Human Torch): Gymnastics

Loki Laufeyson: Figure Skating

Darren Cross (Yellowjacket): Gymnastics

Arcade: Fencing

En Sabah Nur (Apocalypse): Competitive Dance

Scott Lang (Ant-Man): Gymnastics

Erik Lehnsherr (Magneto): Track

Raven Darkhölme (Mystique): Ballet

Charles Xavier (Professor X): Swimming

Teams

Volleyball
Stark
Storm

Soccer
Rogers

Basketball
Banner

Tennis
Barton

Baseball
Blake (Thorsdóttir)

Skateboarding
Maximoff

Figure Skating
Romanoff
Mathews (Lokisdóttir)

Ballet
Maximoff
Darkhölme

BMX
Wilson

Hockey
Howlett

Karate
Summers

Fencing
Summers
Johnson (fake last name since Arcade's last name isn't known.)

Horse Racing
Grey

Roller Derby
Monroe

Competitive Dance
Parker
Jacobs (fake last name for Apocalypse's child.)

Track
Richards
Lehnsherr

Gymnastics
Storm
Cross
Lang

Swimming
Xavier