Hi 
I just taught my Haunter Dream Eater, and noticed that it was listed as a 'mon that couldn't learn the move via TM, yet still allowed me to do that. I'm presuming the display showing if the 'mon can learn the move or not is incorrect, or Haunter can learn a TM they shouldn't. Probably buggy display, though.
EDIT:
To make it clearer, I used the TM on the Haunter, and it was listed as "can't learn", but still allowed me to replace a move with the TM move. Didn't work with any other 'mons that were listed as "can't learn", so I'm inclined to think a text glitch or something.
I just taught my Haunter Dream Eater, and noticed that it was listed as a 'mon that couldn't learn the move via TM, yet still allowed me to do that. I'm presuming the display showing if the 'mon can learn the move or not is incorrect, or Haunter can learn a TM they shouldn't. Probably buggy display, though.
EDIT:
To make it clearer, I used the TM on the Haunter, and it was listed as "can't learn", but still allowed me to replace a move with the TM move. Didn't work with any other 'mons that were listed as "can't learn", so I'm inclined to think a text glitch or something.