In Zero Mission, he is completely biological. Samus blows him up and burns him to a crisp. Then she blows up an unfinished robotic statue of him and the ship that it was on.
In Prime, High Command collects him, sticks him on the Frigate Orpheon ,and decides that since normal Ridley and Mecha-Ridley were not strong enough to beat Samus on their own, the Space Pirates should try combining them and revive him as a cyborg. Meta Ridley is born. Outside of a patch of exposed flesh on each of his extremities, his body is mostly robotic: His wings are mostly energy projections and his neck/spinal cord/head seem to be metal. Samus beats him, he gets fried by the Chozo defense systems, falls off a cliff into the Impact Crater, and explodes. Then shortly after that, the Impact Crater where he landed explodes.
Then in Corruption, Omega Ridley shows up. He has larger gaps in his armor, his head is organic and instead seems to be wearing by an armored faceplate instead of just having metal skin, his regenerated neck is exposed, he has still wounds from getting shot in the chest and laserbeamed off a platform, and in general he is a way easier fight than in the first game despite recycling a lot of the same attacks and animations. Samus tears off the armor on his torso, overloads him with Phazon, and vaguely blows up him up (or something).
In SR, he has lost the face-mask, the armor on his his torso that Samus dismantled in the previous fight is still gone, his wings are organic again instead of being projections (though the fingers of them still seem to be encased in metal), his neck is almost completely exposed, and he is missing even larger, asymmetric chunks of his armor all around his body. Samus and the Hatchling double-team him in the face, blow up some of his components, and then knock him unconscious. After Samus inexplicably walks away without blowing his head off and torching his corpse, he at the bare minimum loses all of the armor that was covering his left arm before leaving SR388.
By the time he gets to Ceres in Super, the robotic components are all gone and after several games he seems to have entirely healed his body back to the state it was in during Zero Mission. Samus blasts him to literal pieces and then blows up the entire planet his body was on, canonically killing him.
Then in Other M, he gets cloned and it turns out that he is basically anime-Charizard, and being evil is just him acting out due to over-leveling and evolving too fast despite technically being a trade. A bunch of silly things happen, and then Clone Ridley gets his life sucked out by a Metroid Queen. For some reason he does not disintegrate into powder at the slightest touch like other Metroid victims, and his dried corpse is taken to the BSL.
In Fusion, his clone's desiccated corpse gets eaten by the X, which mimics his appearance until Samus blows it up and absorbs it.
I think one of the reasons Nintendo is reluctant to do a post-Fusion game is that Sakamoto has no idea how to do a game without Ridley (Returns reinforces this theory!) and Fusion makes it a little difficult to write a game *with* him.
Kinda the same deal as the Zebes/SR388 conundrum.
"Still Samus Returns kinda explains why Ridley is red in the concept art from Super Metroid."
As in later games, all the bosses in Super turn red/orange-ish as their health gets lower and lower (and the Hatchling turns yellow under the same circumstances). Ridley is just near-death in Super Metroid's boxart.