Mother Brain (マザーブレイン,Mazā Burein?) is the main antagonist of the Metroid series. Mother Brain is a cold-hearted and ill-tempered biological supercomputer created by the Chozo, but turned against them when the Space Pirates and Ridley invaded Planet Zebes.
Mother Brain appears as an Assist Trophy, and will fire a beam from her eye as well as rinkas. You can tell when Mother Brain is about to attack when the glass breaks. The beam will rack up multiple hits and cause lots of damage.
Hailing from the Metroid series, this evil boss resides on the planet Zebes. When she appears in Smash Bros., she attacks with energy projectiles and a beam from her eye. It's actually possible to defeat her, and for once doing so won't start a self-destruct sequence.
Though it is based on Mother Brain's appearance in Metroid: Zero Mission, it has attacks from her time in Super Metroid.
It is possible to defeat Mother Brain.
You cannot absorb or reflect Mother Brains attack, so it's best to try to avoid it.