Power: 500 G
Subterra Cycloid is Billy Gilbert's Guardian Bakugan found in the heart of Bakugan Valley. Cycloid is tough and eager to fight. His abilities include 'Left Giganty' and 'Right Giganty' which destroys the Gate Card he stands on, 'Stare Down' which creates a field that lowers the G-Power of any enemy Bakugan that steps in by 50 and 'Smack Down' which he destroys the opponent's gate card by his hand
He is sent to the Doom Dimension by Masquerade like the Guardian Bakugan of The Top Brawlers but was reunited with Billy later.
Cycloid often calls Billy, "boss", and often finds humans amusing and hard to understand, as proved alongside Julie's Gorem. He and Hammer Gorem battles agains Midnight Percival
- Ability Cards
- Smack Down:Destroys Opponent's Gate Card.
- Right Giganti:Nullifies opponent's Gate Card.
- Left Giganti:Nullifies Opponent's Gate Card.
- Stare Down: Cycloid creates a red border to fit nine Gate Cards, and each Bakugan's power level besides Cycloid's is decreased by 50 Gs.
- Boom Hammer:Nullifies opponents ability.
- Skip Hide:
- Stealth Swing:Reflects opponents ability.
- Rocue Punch:Subtracts 400 Gs from the opponent.
- Giganti Hammer:Subracts 150 Gs from each opponent.
- Earth Strike:Nulifies opponent's Gate Card.
- Boom Boomerang:Nulifies opponent's abilities.
- Giganti Punch:Subtracts 200 Gs from each opponent.