BxR, BxB, and Double Shotting were legal in MLG during halo 2. Superbouncing was not legal. Personally I loved all of these glitches because as Skittlze said they provided seperation. Double shotting and BxR'ing effectively did take skill because you needed headshots to get the kill, and double shotting was not an easy glitch to master. BxB was useful as well; although not as effective as BxR it was helpful if you didnt have a BR or Carbine.
Superbouncing provided hours of fun in custom games trying to master bounces and get to never before reached places. Combine that with sword cancelling and butterflying, and you could glitch out of most levels in the game. These elements will never be put back in any game, but I still cherish the fun they provided.
By the way yes I and many others used to superbounce in matchmaking. It was too much fun sniping people from out of maps to not do it.
I could superbounce on top of lockout, ascencion, burial mounds (out of map), zanzibar(on top of the wheel, roof, and out of the map) , headlong (crane and out of map), foundation, warlock, turf (out of map), sanctuary (in the tree haha) , and terminal (out of map).