[Aria]

pikachu and meowth are great partner choices if you ask me since meowth learns hypnosis wich is really helpful skill and pikachu has discharge.

I think you should level up 1st and then use the quick attack on the sableye(both you and your partner,since it's got a good range) that you got closer but use a sleep seed on dusknoir first,take care of the sableye before worrying about dusknoir and make sure to have plenty of oran berries and a few revive seeds (I never go to a dungeon without 1)