It looks like the final Samus of the day is the one with no suit on. Zero-suit Samus is herself as playable in her undergarment, which is different depending on which game you’re playing, but for this skin, that would be the modern generation design.
The corrupt and unstable phazon suit from Metroid Prime. While this suit allowed Samus to move freely through toxic environments, it also was killing her slowly. This same theme was repeated in the third Metroid Prime game, but no one seemed to notice the similarity.