Notes:

Here’s some info on him that I found on the Axetale wiki.

Mettaton is a shattered husk of himself, his own machinery integrating with his soul inseparably and stealing all but the dregs of his mind and memory. He was trapped inside his resort, when the killing started, and was nearly destroyed by the mob of crazed monsters trapped inside with him. He only survived by fusing his cracking soul with his mechanical body, and has forgotten all that he was before the robot. The Hunger has stripped him of all aspects of mercy, and he stalks the halls of his destroyed shrine to beauty, and the Core, haunting the corridors with loud, staticky regurgitations of his television show, interspersed with insane laughter, weather reports, and old interviews/conversations.

He is relatively harmless in his square form, only utilizing it to move, but once he has cornered prey, his back unfolds, revealing his ravaged, nearly destroyed EX form, little more than dismembered, sparking limbs held together with what remains of his magic. His EX form is deadly, strong beyond compare and, even in its state, nearly indestructible; he is merciless, and always hungry, and any monster that he catches is as good as dead, subjected to his television commentary as they are consumed alive.

Mettaton has many of the same foibles as he did before the Hunger. He is weak to praise, fashion, and daring posing, but these do not distract him from his starvation long. The best way to escape him, if you have the misfortune to find yourself in his presence, is to sing him Napstablook’s song. He will malfunction terribly, his machinery denying the memory but his soul crying out for his lost family, and he will retreat to regroup and attempt to calm his irritation. You had better run fast and hide well, though, because he will come back with a vengeance, and will not be able to be redirected again.