Movable Pipe

Movable Pipes, also generically referred to as Green Pipes, are resource items and a variation of Warp Pipes that first appear in Mario vs. Donkey Kong: Mini-Land Mayhem!

Mario vs. Donkey Kong: Mini-Land Mayhem!
Movable Pipes appear as transparent Warp Pipes with dotted line outlines, but when the player taps them with the touchscreen, they turn into fully functional Warp Pipes. The player has only two such Warp Pipes at their disposal, regardless of the number of pipe outlines in a level. Entering into an already existing Warp Pipe leads to the other non-outlined Movable Pipe, or vice versa. A Movable Pipe that is not connected to another end will simply lead the Mini in and out of the same pipe. They are first seen in Area 4-1 of Warped Mansion and appear as a common mechanic of that attraction. Movable Pipes only appear in the color green to distinguish them from other Warp Pipes.

Mario vs. Donkey Kong: Tipping Stars
Movable Pipes also appear in Mario vs. Donkey Kong: Tipping Stars where they are introduced in Level 4-1 of Crumbling Cavern. They behave the same way as they did in Mini-Land Mayhem!

Mini Mario & Friends: amiibo Challenge
In Mini Mario & Friends: amiibo Challenge, Movable Pipes are first encountered in Level 10. They retain their functions from the previous titles, but their outlined form appears to be a much greyer color.