Kirby Hub Room is a solostage in Super Smash Flash that serves as the setting for Target Test. The stage is directly ripped from the Copy Ability Testing Room in Rainbow Route of Kirby & The Amazing Mirror, albeit with a blank white background instead of the original one. All characters have access to this stage when playing through Target Test, but each character has a different arrangement and position for the targets. Despite the name, it is more a general stage for all characters rather than being Kirby-centered only.
Kirby Hub Room is a large stage with four sets of six soft platforms fairly distanced from one another. Underneath these platforms is a hard platform with a wall on either side extending past the platforms, and there is a ceiling connecting to the tops of each wall. There are no blast lines on this stage, with the walls and ceiling preventing the player from exiting the stage boundaries.
As previously mentioned, the sprites and layout of Kirby Hub Room are completely ripped from those of the Copy Ability Testing Room from Kirby & The Amazing Mirror. This room is located in Rainbow Route's starter chamber, Central Circle. It can be entered through a golden-bordered mirror, which becomes accessible after the player presses all of the game's Big Switches, and it serves as the starting area of the game's Boss Endurance mode. Like other testing rooms in the Kirby series, it contains Copy Pedestals for Kirby to access any of the game's Copy Abilities (with the exceptions of UFO and Master).