Hey Ho

From Sonic Retro

The battle with Hey Ho (ヘイ・ホウ) at the end of Mushroom Hill Zone Act 1 is the standard "easy first zone boss." You will just have to wait for it to stop chopping and float down before hitting it. You can attack twice in this period if you're quick enough. Don't touch the boosters underneath the chopping bot either because they will harm you if you aren't equipped with a Fire Shield. Dodge the wood if you need to and after six hits, the fight will be over.

Sonic & Knuckles Sub-bosses
Hey Ho (MHZ) | Gapsule (FBZ) | Guardian (SZ) | Lava Reef Zone Sub-boss | Death Egg Zone Sub-boss
Sonic & Knuckles Bosses
Jet Mobile (MHZ) | Flying Battery Zone Boss | Egg Golem | Lava Reef Zone Boss | Hidden Palace Zone Boss | Sky Sanctuary Zone Bosses | Death Egg Zone Boss | Death Egg Zone Final Boss