Item Abuse in SMM/SMM2 is vastly different than the three ROM-hacks created by PangaeaPanga. Item Abuse in Super Mario Maker is mainly focused on holdable "Items" that are in the game. It ranges from Shell Jumps and Midair Item tricks, to extremely difficult item juggling levels.
"I just watched a video of an ItemAbuse (SMM2) level called 'Shutdown' by Random5314."
A tactic in Mario Kart, in which a player purposefully enters a lower position in order to obtain better items, followed by the player taking said items into higher positions in order to use them where they shouldn't, and wouldn't, normally be able to.