Hmm...
Milotic
Garchomp
Swampert
Blastoise
Aerodactyl
Good choices and funny enough I had a Blastoise on my old team with Rhyperior as well. I could have Blastoise once more on my team, but was hoping to mix it up a bit. I'll have to look around to see what I decided to do first.
Having a Dragon-Type is good as well, though being weak to Dragon, Ice, Fairy-Type is a disadvantage so having a Dragon-Type with resistance to Fairy-Type would be handy.
Not sure on Swampert with his 4x weakness to Grass-Type moves though he is tanky a bit. With Mega Evolution I was thinking having Charizard take on the Fire-Dragon Type slot, thought Garchomp is powerful as I had trouble with him in Diamond/Pearl/Platinum.
Then again Aerodactyl has the fastest Mega Pokemon in the game and his Mega Form is beastly too I hear.
Though having a Water-Type like Milotic is nice to fill the gap, but it's a Pure Water Type. Hoping for some Dual Type Pokemon to help cover the field a bit.