Rainbow Cap Switch

The Rainbow Cap Switch is an anomalous cap switch similar in nature to the Yellow Cap Switch. It is reported to be found in secret levels added by the Personalization A.I. or in place of other cap switches, most commonly replacing the Metal Cap. The Rainbow Cap Switch is reported to usually be found as a "final power-up".

Upon pressing the Rainbow Cap Switch, it usually unlocks special abilities such as the special triple jump given by Yoshi, or special caps such as a cap that activates all 3 cap abilities at the same time. However, it can also supposedly unlock the Rainbow Cap or Starman, which are considered identical power-ups.

Rainbow Cap / Starman
The Rainbow Cap and Starman are reported to act similarly to the Metal Cap and Koopa shell, most commonly giving the player invincibility and the ability to run through enemies and breakable objects. They also usually allow the player to walk underwater. They have also not been reported to have the "weight" of the Metal Cap. The Rainbow Cap and Starman are occasionally reported to be somewhat unstable, sometimes causing the game to crash, with the Starman being more unstable than the Rainbow Cap.

It is believed that the Starman was scrapped early in development, as it is a power-up seen in other Super Mario Bros. games similarly to the Fire Flower, then replaced with the Rainbow Cap to fit with the other cap power-ups, before finally being replaced with the Metal Cap. The Personalization A.I. would then bring back the Rainbow Cap Switch, sometimes without the Rainbow Cap or Starman.