Metroid Database.com

As usual with the Metroid games, the ending of Metroid II has a standard beginning, and the difference comes when it's time for Samus to reveal her identity.

1. Samus finds an egg which hatches, and a little baby metroid emerges and clings to Samus, thinking she's its mother
2. After making her way to SR388's surface (the player controls this), Samus hops into her ship with the metroid hatchling, the screen fades out and the ending theme starts.
3. Samus is shown on the right side of the screen, in her armor, running toward the player (but in place), with a star-filled background. The credits start scrolling on the left.
4. The credits end, and away we go...

ENDING ONE | Image

(< 3 hours)
Samus leaps up out of frame, and when she lands, her armor disappears and she's wearing a bikini bottom and tank top.

ENDING TWO | Image

(3-5 hours)
Samus leaps up out of frame, but when she lands, her armor stays put.

ENDING THREE | Image

(> 5 hours)
Samus just continues running in her armor.