Lets see
I see a lot less weezings now, I never played competitive advanced, but from what my research of past gens show weezing was pretty good, now I rarely see it.
Blaziken got murdered. No question about it, infernape just raped it.
Alakazam took a huge hit thanks to the returning popularity of pursuit
Medicham went emo when shadow ball got switched to special
Tyranitar is an even greater beast thanks to physical crunch, pursuit, sandstorm special defense upgrade, and stone edge.
Salamance had become feared with extent, now that he can go both ways.(no homo; special and physical you pervs)
Gyarados is even scarier thanks to the likes of taunt and stone edge
Heracross wen from an ok stab to an insane stab along with stone edge, pursuit, and night slash
Raikou somehow got lost, I always thought he was great, guess he's too predictable
Snorlax died, I mean you give a monkey slack off and you don't give the classic sleeping pokemon slack off? Whats wrong with that picture?! Close combat isn't a fresh new look at things for him ether.