Mario and sonic have gotten so fed up with each other lately that they've started fighting each oter and the others have gotten involved as well, even Eggman and Bowser
Soldier (Attacks with weapons (no guns though)) - Yoshi
Sniper (Hit and run tactic) - Luigi
Scout (same as sniper, but can move faster) - Joey
Pyro (Attacks with fire) - Bowser
Demoman (attacks with bombs and explosions. Also used bombs to act as shields for bases) - Spark
Engineer (uses gadgets both to attack and defend) - Professor E Gadd
Medic (Heals allies, but can also attack by poisoning enemies) - Mario
Heavy (Smashes through enemy troops to protect based) - Wario
Spy (Disguises as others to learn of enemy plans and pull sneak attacks) - Bowser Junior
(Yes these are TF2 classes but obviously turned down from the game for obvious reasons
Tell me who's who on Sonic's side, and let's start with Junior being discovered and captured to be used as ransom to get the one they want (which could be whoever you want)
...
Junior slowly opens his eyes. He ached all over, and his vision was blurry. He blinked and rubbed his eyes to see "Where am I...?"