Metroid Prime

Classic Metroid game:
Note: This trick requires Metroid Fusion, a Game Boy Advance, and a link cable. Successfully complete Metroid Fusion and save the game. Connect both games with the link cable to unlock the classic NES version of Metroid.

To unlock the classic Metroid (via a link cable,Game Boy Advance, Metroid Fusion and completed Metroid Prime data), press Z at the main menu to highlight "Password", then enter JUSTIN BAILEY ------ ------
Andrew Mooney.

Metroid Fusion costume:
Note: This trick requires Metroid Fusion and the Game Boy Advance and a link cable. Successfully complete Metroid Prime and save the game. Connect both games with the link cable to unlock Samus' Metroid Fusion costume.

Image Gallery 1 option:
Complete 50% of the research and creature data scans.

Image Gallery 2 option:
Complete 100% of the research and creature data scans.

Image Gallery 3 option:
Successfully complete the game under the hard difficulty setting.

Image Gallery 4 option:
Find 100% of all power-ups. Note: This does not include the Log Book.
Preps Always Suk.

Note: The last picture in this gallery is that of Samus without her suit in 3D.
Mason.

Hard mode:
Successfully complete the game to unlock hard mode.
Jonathan Swerski.

101% completion:
This is extremely difficult to achieve, and you may not get it on your first attempt. To get a 101% completion rating, play the game under hard difficulty setting you have completed the game once. Then, go through the game again, collecting every single power-up, expansion pack, and anything else. Make sure you did not miss a single one. If you manage to collect every item within the game (you should get confirmation messages for it), and complete the game, you may end up with 101% as a completion grade.
Ryan Lauck.

Alternate ending sequences:
Finish the game with a 74% or less completion percentage for the normal ending sequence. Finish the game with a 75% to 99% completion percentage to view an alternate ending sequence. Finish the game with a 100% completion percentage to view the best ending sequence.

If you defeat Metroid Prime's second form with 74% or less items, the intermission sequence will show you losing your Phazon suit and the Artifact Temple about to explode. After Samus calls her ship and jumps onto it, you will hear a voice saying that the Chozo's were right to believe in Samus. After that, you will see Samus just about to remove her helmet and it starts the credits.
Luke Kovacs.

If you defeat Metroid Prime's second form with 75% or more items, the intermission sequence will show you losing your Phazon suit and the Artifact Temple about to explode. After Samus calls her ship and jumps onto it you will hear a voice saying that the Chozo's were right to believe in Samus. After that, you see Samus remove her helmet and stare at the temple for awhile. The credits will then start.
Luke Kovacs.

If you defeat Metroid Prime's second form with 100% items, the intermission sequence will show you losing your Phazon suit and the Artifact Temple about to explode. After Samus calls her ship and jumps onto it you will hear a voice saying that the Chozo's were right to believe in Samus. After that, you see Samus remove her helmet and stare at the temple for awhile. Then the camera shows a rippling mass of Phazon in a cave. A black and red metal hand will burst from the Phazon. You then see an alien eye-like object behind the hand look around the place. The credits will then start.
Luke Kovacs.