Fight till death or KO
Fight two rounds both teams have 2 days prep both rounds Team USA has shield tech and Shadows has Jl tech but nothing ridiculous(if it's an instant win it's ridiculous). Terry has old Wayne in his comm talking to him.
First fight in Avengers Mansion, second in JL Watch Tower neither teams had knowledge where they would fight.
Batman, Nightwing, Cassandra Cain, Deathstroke, Batman Beyond, Batman(Damian), Batgirl(Barbara), Red Robin, Red Hood and Cyborg.
Captain America, Daredevil, Winter Soilder, Black Panther, Spiderman(Peter), Wolverine, Black Widow, Moon Knight, Punisher, and Ironman.