I've been hovering around the thread awhile, but I must say that I can't hold my peace any longer when some Metroid-related information is wrong. Although your link of Dark Samus was accurate, it's only as accurate as what she looks on the outside. Although Metroid Prime is inside the suit, she looks almost identical to Samus, just as Sa-X did.
Here's a more accurate referrence picture of her:
What is really inside that phazon armor.And I think it would be amazing if it was actually a group scene of Samus, Sa-X, and Dark Samus. Dark Samus could be in front with a "Phazon-Penis" (or simply "Phanis") that shoots a load of phazon-filled cum when finished. On the other end, you'd have Sa-X licking Samus' girly bits while fingering herself in the process.
It may just be my opinion, but I think that scene would be the most epic, and erotic flash scene ever conceived that involves Metroid.
Tentacles can be included with the fact that Dark Samus can morph her body with Phazon tentacles...Dark Samus can also multiply herself and teleport around...
Yeah, I'd say Dark Samus VS Samus in a Playshapes themed flash game is just about the best flash ever!