Even if those designs are 'out there', they still had intentions that were in line with the world at the time and/or served as an alternate take on classic monsters.>Eggs
Actually coconut tree seeds. Their entire concept is subversive to both yours and their environment's expectations, especially with Pokemon like Ekans and Pidgeotto that prey on eggs and seemingly weak Pokemon. By merit of being a Psychic Type, Exeggcute can effortlessly ward off predators and foes alike.>Piles of sludge
A unique take on the classic slime monster as seen in every RPG ever, being the result of humanity's pollution gaining a life of its own and coming back to bite them in the ass, which is a major theme in Kanto's urban, industrial environment. Also an explicit reference to Hedorah, which in turn puts a spin on the Pocket Monster concept by compacting the iconic Smog Monster itself into a smaller, easily-contained, easily-commanded form.>Magnets
Doesn't appear to have any clear inspirations, but Magnemite is in line with the familiar concept of floating eye monsters, albeit modernized, most likely to go with the aforementioned urban, industrialized setting.>Toxic smoke bombs
Once again another prime aspect of Kanto's theme, very clearly representing man's weaponization of pollutants, even going as far as to very easily be seen as Grimer's partner in crime between similar BSTs and being found in the same area exclusively: Koffing's the "cause", Grimer's the "effect".