Mushroom Kingdom II
Mushroom Kingdom II (いにしえの王国II, Ancient Kingdom II) is an unlockable stage in Super Smash Bros. Melee and a starter stage in Super Smash Bros. Ultimate; in Ultimate, its Japanese name has been changed to いにしえの王国 USA (Ancient Kingdom USA), to better reflect the Japanese title of Super Mario Bros. 2, Super Mario USA.
In Melee, Luigi is fought here for his unlocking battle, even if this stage itself is not unlocked yet. However, if the player has not yet obtained the Birdo trophy, they do not unlock the unlockable stage. In All-Star mode, this is where the player faces Dr. Mario and any of his teammates.
The stage has three hard platforms, all of which reach the bottom blast line: two at the sides, and a lower one in the middle (which is actually made up of two pieces of ground connected by a log).
Logs continuously come down from the waterfall in the background, acting as temporary platforms which quickly fall down into the two pits on the sides of the center platform. These logs are completely solid and cannot be passed through so getting caught beneath one once it has entered either pit is a guaranteed KO.
Occasionally, Birdo appears from either side of the screen and shoots eggs, either one or three. These eggs can be attacked, knocking them off, or caught aerially: if thrown at an opponent they deal massive damage and knockback, up to 28%. After being caught and thrown the eggs can be broken, and sometimes contain items. Birdo is susceptible to attacks, and if damaged enough she retreats, or can even be knocked off stage. Sometimes Pidgits will fly erratically over the middle part on a carpet, which can be jumped on.
Ω form and Battlefield form
In Super Smash Bros. Ultimate, the Ω form and Battlefield form are set in the air in front of a waterfall, and the main platform is based on the grassy soil of the regular form. The main platform also does not extend below the blast line and is resized and reshaped to match Final Destination. Walk-offs are removed and Birdos, Pidgits, and logs do not interfere with the stage. The design of the three soft platforms of the Battlefield form are based on logs of the regular form.
Contrary to what its name suggests, this stage is not derived from any version of the Mushroom Kingdom; it originates from Super Mario Bros. 2's World 1, which takes place in the land of Subcon. The graphical style is based on the SNES port of Super Mario Bros. 2 included in Super Mario All-Stars (especially in Ultimate, where the actual graphics are used), rather than the original NES version.
Waterfalls are a common element in World 1 of Super Mario Bros. 2, and often have logs coming down from them that can be used as temporary platforms.
Pidgits are small bird enemies that ride on flying magic carpets in Super Mario Bros. 2, debuting in World 1-2. When they are defeated, their carpets can be ridden and controlled by the player, though these vanish after a short while.
Also in Super Mario Bros. 2 are Birdos, which are recurring mid-bosses that are fought in most levels. The pink ones attack by solely shooting eggs, which can be picked up and thrown to defeat them.
For several reasons, this stage is banned in competitive play. The stage is commonly seen as too small to hold a proper competitive battle on, and Birdo's appearances are random and overly disruptive to the matches. The walk-off blast lines can additionally result in quick, easy KOs, and the lack of a proper "central" platform serves as a hindrance, particularly in doubles matches.