Devilstar

The Mecha Planet is a planet from the Generation 1 continuity family.

What if Dr. Wily replaced Dr. Arkeville?

The Mecha Planet (メカ惑星 Meka Wauksei) is an offensive weapon used by the Decepticons. It sends out Kabusu to attack.

Fiction

Transformers (Mystery of Convoy)

Ultra Magnus confronted the Mecha Planet, which attacked with Kabusu. Avoiding them, Ultra Magnus transformed into vehicle mode, positioned himself underneath the Planet, and shot it, defeating the Planet.

Ultra Magnus would later confront the very similar Twin Planets. Use Trailer Mode to Defeat the Mecha Planet!

Alternity

The Mecha Planet or the Twin Planets were shown as enemies to overcome for Optimus Prime's representative in Megatron's game. To Die Game!