Here is a list of Pokémon with highly specific, non-combat biological death conditions according to canon Pokédex lore:
• Spoink: If it ever stops bouncing its heart immediately stops beating.
• Charmander: If its flame is ever completely extinguished by a heavy rainstorm or water, it dies.
• Slugma: It must stay in constant motion to keep its body temperature up or its body cools, hardens into rock, and it shatters.
• Applin: It is born as a tiny, vulnerable dragon that must immediately burrow into an apple to survive. If it is ever separated from its apple and cannot find a replacement, its body rapidly dries out and it perishes.
• Minior: When it falls to earth and the shell breaks, its colorful energy core is exposed. It will quickly fade away and die unless it is immediately stabilized by being captured in a Pokéball.
• Jumpluff: It travels the world by catching the wind and scattering its cotton spores to reproduce. It operates on a strict, unchangeable biological timer: the exact moment it runs out of spores, its life ends.
• Klang: Its body consists of two living gears, and it attacks by firing its smaller gear at enemies. If that minigear misses or gets lost, Klang's biological machinery permanently seizes up, and it dies.
• Jigglypuff: When it begins to sing its lullaby, it doesn't pause to take a breath. If it encounters an opponent with that is hard to fall asleep, it will continue to sing until it literally suffocates itself.
• Primeape: It can get so unbelievably mad that it literally dies of rage—though the Pokédex morbidly notes it finally looks peaceful in death.
• Parasect: If the mushroom is ever forcefully removed, the bug's body stops moving permanently.
• Paras: Evolving
Am I missing any, and was anyone on this list surprising to you?