I beat Fusion in under 1h50m. Does that count? Best completion was 81%
As for the first Prime. For 74% and under, you get the normal ending.
For 75% and above, you get the same ending except Samus takes her helmet off.
For 100%, you get to see Dark Samus' hand pop up out of a pool of Phazon.
In Prime 2, for 75% and above, Samus removes her power suit and you get to see her in the Zero Suit.
For 100%, Dark Samus materializes in outer space and makes a subtle gesture towards the camera (it's a far away shot, so it's hard to notice). Yours truly got this ending on Hard Mode on the GameCube. Took me a month.
Lastly, corruption. The 75% ending is the same as Prime 2.
The 100% shows Samus' ship going to warp and another ship following.
You're welcome.
