Metroid Prime cheats and cheat codes for Gamecube

Normal ending:
Finish the game and reacch 74% or less completion

Different ending:
Finish the and reach 75% to 99% completion 

Best ending:
Finish the game with a 100% completion

Samus without suit in classic Metroid ending:
Finish the classic Metroid game less than 2 hours

Unlock Image Gallery 1 option
Finish 50% completion of the research and creature data scans 

Unlock Image Gallery 2 option
Finish 100% of the research and creature data scans 

Unlock Image Gallery 3 option
Finish the game on hard mode

Unlock Image Gallery 4 option
Find 100% of all power-ups

Unlock Hard mode
Finish the game with a 100% completion

Fire missiles faster
With the first gun equipped, rapidly hit Y + A, then 
hit Y again when the gun switch back to beam weapon mode

Unlimited health
While playing the game on any level, press  L,R,L,R,L,B,Y,Z
(This cheat is not tested!) 

Classic NES version of Metroid and Samus' Metroid Fusion costume:
Note: You need Metroid Fusion and the GBA link cable to do this.
Finish Metroid Fusion and save the game after connect both games 
with the link cable.