If there are multiple, name all. Also nothing post-game.
Only two Pokemon that can be obtained in in-game trades with erratic experience group. They are:
Cranidos (Pokemon Black 2/ White 2, from Curtis if player is female)
Shieldon (Pokemon Black 2/ White 2, from Yancy if player is male)
Source 1 Source 2
I copied each Pokemon from Source 1, then searched for it in Source 2. Only these two were found.
Hope this helps!