I reckon all the 3 stage evolutions will be as big as the dragonites.
I'm level 22, I've got a 690cp oddish, the Vileploom would be 2000cp+
I've got a 590 charmander, the Charizard would be huge.
Vileploom, Victrebell, Charizard, Venasaur, Blastoise, Nidoking etc look all as potentially big as Dragonites