Much like another anon's already said, EQ is probably one of the best moves (along with Ice beam and maybe Psychic ?) in the game because it offers good power, great coverage and is very very widely available, without a single drawback; so it just makes sense for it to be omnipresent since every smart trainer would just slap it on every Pokemon that can learn it
Ultimately, because of Pokemon's basic battle mechanics, the only way to make AI opponents challenging is either:
>you give their mons a 5/6 levels advantage over the average trainer of their respective area>you build their team around a competitive strategy and give them very strong sets (this is the way that some fangames approach this problem, and trust me when I say that fighting a gym leader that runs 6 stallmons doesn't make for a rewarding experience)>>44760616>>44755685>this fanserviceHuh I always assumed those hacks just covered fights and wild encounters, never thought they'd make changes to the characters and story too (I assume the main quest is still intact and he's just added some little easter egg encounters)