Even if you get all those Pokemon yourself, you still wouldn't get the national dex until after you beat the Elite Four though, right?Wasn't trying to bite heads, just you could've put in a second or two to check. Sorry, I have a fiery temper...
The E4 exclusives that aren't anywhere else in the game (unless you do it yourself) I believe are:
Aaron's Drapion
Flint's Infernape
Flint's Rapidash
Cynthia's Milotic
Cynthia's Spiritomb
Cynthia's Garchomp
Some people have also said that Drifloon is nowhere else in the game but at Valley Windworks and Hearthome Gym, so if you miss it you'll have to wait until Friday.