I never used pokemon like magnemite, grimer, koffing, voltorb, diglett, doduo, staryu, tangela, shellder....sorta just because of how they look with lacking certain limbs and all...idk I'm weird lol. It's just my preference...I will try to use some typically weaker pokemon species, though, like rattata and butterfree for fun though I always ditch them at some point for stronger ones. I also for some reason always try to train a pidgeot, and keep it until just before the elite four, then ditch it because it isn't strong enough (and usually replace it with one of the legendary birds).