Y Mecha is the final boss from Streets of Rage 4. It is a huge six legged robot owned by the Y Twins.
They will assist the other twin by by slamming its claws around the area, occasionally performing a claw sweep that can be evaded by not going on the claw's attack range. If the mech is defeated first, the still active twin will attempt to take its place as its new pilot.
Once the mech's health is reduced to 50%, it will slam its claw furiously on the ground making it harder to evade its attacks.