Rangda Bangda

Ramba (also called Rangda Bangda) is the boss of the second Sigma stage of Mega Man X1. It is the face in the background, and it has moving eyes, a nose gun, and its mouth is a pit of spikes. To make matters worse, it can move its walls inward to try to force X into the spikes. In Mega Man X1, the best weapon to use is Chameleon Sting.

Ramba also appears in Mega Man X5, and it's even harder at this point. X with Gaea Armor is a serious help here!