Mucuscule

X / Omega Ruby: The weakest Dragon-type Pokémon, it lives in damp, shady places, so its body doesn’t dry out.

Y / Alpha Sapphire: It’s covered in a slimy membrane that makes any punches or kicks slide off it harmlessly.

Sun: The weakest of all Dragon-type Pokémon, it’s unable to breathe if its skin dries out, so it sticks to shady places.

Moon: Its source of protection is its slimy, germ-laden mucous membrane. Anyone who touches it needs some thorough hand-washing.

Ultra Sun: It uses its horns to check out its surroundings. They’re very sensitive, so if you grab them, it will feel a strong shock and be unable to move.

Ultra Moon: Its body is mostly water. If it dries out, it will die, so it’s always sitting with perfect stillness in the shade.

Sword: Because most of its body is water, it will dry up if the weather becomes too arid. It’s considered the weakest dragon Pokémon.

Shield: Their horns are powerful sensors. As soon as Goomy pick up any sign of enemies, they go into hiding. This is how they’ve survived.

Legends: Arceus: Goomy hides away in the shade of trees, where it's nice and humid. If the slime coating its body dries out, the Pokémon instantly becomes lethargic.