This Pokémon's gotten worse since Gen I. It went from "one of the best Pokémon ever" (Gen I), to "mediocre" (Gen II-III) then to "So horrendous that it's really easy to defeat" (Gen IV onwards). It really needs one, to help it. Machamp doesn't need one. It can last longer in battle anyway.
5. Magneton because, and I quote: "Magneton emits a powerful magnetic force that is fatal to mechanical devices. As a result, large cities sound sirens to warn citizens of large-scale outbreaks of this Pokémon"
Now, gimme 5 Pokemon that would be better if they had different colors.