"It never sleeps. It has to keep moving because if it stopped, its magma body would cool and harden." (Pokemon Gold)
Life did not deal Slugma a good hand it is literally just a blob of magma given unnatural sentience. And, to top it off, it can never sleep hell, it can't stop constantly moving. Even sharks which also need to constantly move have figured out a way to swim-sleep. Not Slugma it can never experience rest, in any form, ever. On the other hand, at least it doesn't have to worry about getting its dreams eaten by ghosts (which REMINDER! is an actual thing that happens to Pokemon).
"Spoink bounces around on its tail. The shock of its bouncing makes its heart pump. As a result, this Pokémon cannot afford to stop bouncing if it stops, its heart will stop." (Pokemon Ruby)
There are a lot of things we can do without really thinking about it we breathe, blink, and have our circulatory system get the job done without having to tell each individual organ what to do at every second. Spoink doesn't have that luxury it needs to constantly bounce on its own tail just to keep its heart beating like the least efficient, most frustrating pace maker ever conceived. If it sleeps, it dies. If it stops bouncing to take a rest, it dies. And it probably needs to keep bouncing at a very steady, precise pace if it's too slow, it would pass out from too-slow bloodflow; if it's too fast, it could have a heart attack. At least bacon's probably pretty easy to come by in the Pokemon universe.
"They cannot see, so they tackle and bite to learn about their surroundings. Their bodies are covered in wounds." (Pokemon White)
Blind people have it bad but at least they have the common sense to get walking sticks, seeing-eye dogs, and use braille to try to make do with every day life. Deino does not seem to know how to adjust to blindness and has decided to fling itself and snap its jaws at everything in an attempt to get by. Given that its entire body is covered in wounds constantly, to the point where its part of each one's physical descriptions, it must be pretty miserable. Blind and in pain at all times. If only someone would give it a haircut.
"Always tormented by headaches. It uses psychic powers, but it is not known if it intends to do so." (Pokemon Yellow)
Well, Psyduck's life sucks. Not only is it constantly wracked by migraines (likely caused by a brain tumor or some other horrible brain ailment), but it has powers that it uses even though it doesn't mean to. It could be zapping the minds of its loved ones and not even realize it. And the only possible hope for these poor creatures is to be enslaved by a parentless 11 year old and battled until it evolves into Golduck. And then, if it's real lucky, it'll be put into a computer for the rest of it's life, where it won't be using psychic brain blasts unwillingly and the headaches can finally end.