Lucario has two weaknesses Hydreigon covers well. Unfortunately, it won't take any fighting moves, which also are a problem for Luc. I guess the ability to just come out firing with Hydreigon would help a lot, but Salamence covers all three weaknesses.
Bulk Up Conkelldurr still won't like seeing any bulky ghosts move in (unless you have Payback as well), which look like they'd give this team some trouble. His weaknesses, however, are probably pretty well covered by Hydreigon (which includes the bulky ghost problem, provided it doesn't get T-Waved on a switch).