Cyner
Too little too late
Sorry wamm, but by the end of any of Samus' 2D games she might as well be some sort of demi-god.
Samus is very agile, very fast, and with the speed booster she can run at super sonic speeds, becomes nigh invincible, and crushes anything in her path.
Power Beam, Charge Beam, Wave Beam, Ice Beam, Plasma Beam, all combine to create a weapon of considerable power that can pierce through metal and flesh alike. Additionally the Hyper Beam is far beyond even all of that.
I'm confident that direct rocket strike from a Human rocket launcher of the Halo series would kill the Arbiter with a direct hit. Samus' technology being far above the humans of the Halo series it would only take one of her rockets to kill him. Samus' suit creates fully formed missles from only the energy created in her own suit, which is infinite. Also she can fire five homing missles at once at one target, or 5 different targets. That's more than enough to kill the Arbiter in one salvo.
Bombs, Power Bombs, Space jump, Screw attack... there is so MUCH more that Samus has, this is just a very small sample... Really... the Arbiter stands no chance.