You can press B, and your character will grapple the character you are not using. Alot of times when you do it they do their combo ender, and some characters have some cool ones (Green Lantern, Flash, Superman)
Its also pretty funny to try and grapple someone like Superman, especially with Bane, since its kind of how the fight would go. --- http://www.facebook.com/MEmarauder - Marauder Shields Facebook page.
It's also a really quick way to get the Combo Hero achievement, I found out, when playing with a friend. Turned it on, grabbed him, and BLEEP-BLOOP, achievement unlocked.
Best part is, I've got a history of trolling/griefing him in every game we play together, and I mean EVERY game, so to be able to get an achievement by trolling him was amazing :D --- Moo. Xbox Live Gamertag: SageRamirez00