The signature large shoulders of Samus' Varia Suit debuted here and were born out of necessity. In the previous game, the Varia suit was shown as a pink palette swap of the normal suit.

Because of the Game Boy's limited color palette however (it could only display around 4 different shades of black and white) drastic visual changes had to be implemented to let the players tell the Varia Suit from the normal suit. The Varia Suit was thus given larger shoulders which have since become the most defining feature of Samus' armor throughout the series.

This also affected Samus' Arm Cannon's missile launcher function. In the previous game, Samus' Arm Cannon turned blue when its Missile launcher was active. However, because of the limited color palette, in Metroid II, Missile mode is shown as the tip of the Arm Cannon opening and extending outward which has also been featured in later games.