CHIME NOISES INTENSIFY
I'm surprised no one has mentioned Gyarados yet! Getting a stab physical water move turned Gyarados into an even stronger powerhouse. And also Kingler and Crawdaunt benefited strongly from the phys/spec split. So did Medicham, with physical psychic moves available. (zen headbutt by move tutor, psycho cut by breeding) Also, Hitmonchan was finally able to utilize the elemental punches one they became physical. Mightyena was able to use dark moves more effectively too.
Not too sure of pokemon who didn't benefit from the split. XD