Platforms are a major convenience- even a necessity on Fribbulus Xax. In most places they are used to transport you over dangerous obstacles, or to places out of reach. Many of the platforms(or "plats" as the locals call them) are still the old style which are operated by Bips. Other types of platforms occur on other planets as well.
Switches in Keen 1 and 3 only control lights and bridges; switches in Keen 4-6 only activate/deactivate platforms and bridges. Switches in K6 can be jumped or pogoed off, just as they are flicked downwards.
Keen 1 and Keen 3: The teleporters found on the maps of the games and teleport you to other locations. Keen 5: A teleportation device is hidden in the Gravitational Damping Hub of Keen 5. It leads to the bonus level on the planet of Korath III, the Secret Korath III Base. There is another return-teleporter on the map of Korath III. Keen 6: A teleporter that teleports you to an "underground" portion of Keen VI. Keen GBC: When Commander Keen uses one of these, he pops out of another one in a different area of the level in Keen GBC.