Starraptor is an excellent bird, and a damn useful pokemon for the elite 4, he helps take out the bug E4 member, pretty much by himself (if you have him around lvl 60). Watch out for Drapion though, Use earthquake or aterfall from Gyrados if you can.

Keep Roserade for the second elite 4 member, it kills whiscash and quagsire easily. You can also use Gyrados here on the other members of her team, as they are all ground.

Gyrados is also awesome for taking out the fire member of the elite 4. Waterfall the fire members, and earthquake Lopunny and steelix. If you can teach Gyrados Ice Fang, it can take out Drifblim too.

From memory the fourth elite 4 member was a pain, you need strong dark attacks, (I used Torterra's crunch here). Try and keep Rapidash in reserve for Bronzong, who can be painful.

So I'd suggest training up Gryados, Starraptor, Rapidash, Roserade, Lucario and something else (Id suggest a Bronzong if you have the patience, it's a great wall, and can be used to send opponents to sleep, as well as give you time to heal your other pokemon, if not, go Luxray, it's a more than decent pokemon if it has electric and dark attacks) all to level 55 or so. Once you reach the elite 4, you no longer need your HM slaves (good ol' Bibarel was made for that job!).

Goodluck!