Buyoons are flat, capsule-like Badniks with dark blue and gray armor and hazard stripes across their midsection. They also have two rabbit-like ears, two gray eyes and short legs. Inside their body is a gelatine-like liquid that can grow into a large belly-like blob, with the Buyoons' upper and lower body remaining attached to it. When this happens, the Buyoons' framework are visible inside their belly.
Buyoons are found in either Sonic or Amy's edition of Twinkle Park. On their own, the Buyoons hop around idly in their regular uninflated state. When the player approaches, however, their bellies expand to maximum size and they start walking towards the player at low speed.
While the Buyoons are inflated, they can bounce any attack on their bellies backwards. While the Buyoons will deflate for a limited time to recharge, they will eventually re-inflate and continue their chase. To defeat a Buyoon, the player must attack its head using the Homing Attack or Jump Attack.
- Buyoon's name originates from the Japanese onomatopoeia buyo buyo (ブヨブヨ?), which is used to denote something soft or squishy.