You know I used to love Gyarados, but it's in nearly every game and Magikarp is nearly impossible not to get at some point. It's ridiculous. Then half of the villains and major trainers seem to use it as well. At least one important trainer in every gen besides 5 and 7 has one. And even in 7 there's the Rainbow Rocket bosses. Pretty sick of it now. Gyarados and Geodude lines are the ones I'm sick of the most.
Then you get fucking Venomoth that only appears in Kanto and Johto dexes. Come on man.