Excadrill you won't be getting until after the 4th badge. Half the game is over. Drillbur is not OP at all. It needs Eviolite just to not get OHKOed constantly.
Lucario is a friendship evolution. You likely won't get it until you get to Castelia. Even then, Burgh resists Fighting and Lucario has piss-poor defenses. Until you get to the level 40-50 range, your strongest moves for Lucario will be Force Palm, Return, or Rock Tomb.
In other words, you're full of shit.
If anything, the MOST overpowered Pokemon in BW2 for your party is Magnemite, by far. Even then, you can't even solo the game with it because it shit-all to basically any Ground-type.
Even vanilla BW2 is a nice challenge.