Flipper

Flipper is an obstacle from the game Balloon Fight which appears as an item in Super Smash Flash and its reboot Super Smash Flash 2.

In Super Smash Flash
Because of its appearance in Super Smash Bros. Melee, Flippers were Featured in Super Smash Flash, where they work most likely the same. Players can pick it up and throw it, when thrown, it will hover in the air and begin to spin. Any player who comes in contact with it receives damage. The Flipper continues spinning, while hurting other characters, and after some amount of time, it disappears.

In Super Smash Flash 2
The Flipper is confirmed to be an item in SSF2 Beta and works exactly as it did in Melee, being planted on ground and spinning only if players attack it. It is worth noting that the Flipper will also be appearing alongside the Bumper, the item it replaced in Melee and conversely got replaced back by it in Brawl.