The Doomsday Zone Sub-boss
From Sonic Retro
Official Name and Merge?
According to the JP Sonic Mega Collection guide book, this boss is called ファイナルウェポン (Final Weapon): https://i.imgur.com/0MNMuaS.jpg
It seems to refer to the second phase as Eggman Robo, but I'm not sure if this is just descriptive. Regardless, both phases of the battle are treated as a single boss fight. --Pecky (talk) 16:18, 27 October 2019 (EDT)