The All-Star Rest Area (オールスター休憩所, Ōrusutā Kyūkeisho, lit. "All-Star Rest Area") is a special stage used to warp between battles in All-Star mode throughout all of the Super Smash Bros. games and in Super Smash Flash.
In Super Smash Flash
A stage very similar to Floating Islands. The player can KO itself here without losing, thought it will respawn next to the door and its' damage is kept. If the player goes through the door while it is healing, the healing will stop and the next battle will start.
In Super Smash Flash 2
|This article/section contains information of a feature that is not confirmed to appear on any game or similar media.|
This means that the subject of has yet to be confirmed by an official source for the final build for said material.
All-Star mode currently remain unconfirmed for Super Smash Flash 2, thus, how the Rest Area looks is also unknown.