Cool Kong

From the Super Mario Wiki

A Cool Kong aiding a Mini Mario. Here the Cool Kong is in its lowered form.

Cool Kongs are Mini Donkey Kongs in Mario vs. Donkey Kong 2: March of the Minis.

Originally, a Cool Kong is twice as large as a Mini Mario. However, if a Mini Mario grabs their ties, the Mini Mario will hold on to it, while the Cool Kong moves around. The pressure lowers the Cool Kong by half, and the Mini Mario can hold on as long as he pleases – this is critical to get over long obstacles of water and spikes.

A Cool Kong moves back and forth on the surface it's on, which is often blocked off of normal access by a Mini – except for the tie, which often must be jumped for. When a Cool Kong is lowered, it sometimes travels under another low platform, allowing it to travel farther can it could have without a Mini. Often this is the key to get that particular Mini to the Goal (or even Minis – sometimes the Cool Kong is able to reach a spot where another Mini can ride on top of it, like any other movable platform).