Boolossus
Smash Ace
Most of the time when people refer to this suit, they seem to refer to it as the dark suit from Echoes. I think it more closely resembles the Phazon Suit from Prime 1 more though. Just take a look.
Left side=Dark Suit from Echoes
Middle=Phazon suit from Prime 1
Right side= Samus's Dark costume in Brawl.
Similarities between the Phazon suit and the Dark costume:
-Shoulder pads are same shape, the shoulder pads on the dark suit are thinner.
-Visor is same shape, the visor on the dark suit is less round.
-Shoulder pads are a darker color than the rest of the suit, the shoulder pads on the dark suit are the same color as the rest of the suit.
-Chest plate is shaped the same, the chest plate on the dark suit is more flat.
-Pointed knee plates, the knee plates on the dark suit are flat.
-Armor plating is the same, the armor plating on the dark suit has a more plain style.
Left side=Dark Suit from Echoes
Middle=Phazon suit from Prime 1
Right side= Samus's Dark costume in Brawl.
Similarities between the Phazon suit and the Dark costume:
-Shoulder pads are same shape, the shoulder pads on the dark suit are thinner.
-Visor is same shape, the visor on the dark suit is less round.
-Shoulder pads are a darker color than the rest of the suit, the shoulder pads on the dark suit are the same color as the rest of the suit.
-Chest plate is shaped the same, the chest plate on the dark suit is more flat.
-Pointed knee plates, the knee plates on the dark suit are flat.
-Armor plating is the same, the armor plating on the dark suit has a more plain style.