There really isn't *one* perfect team that can solve any problem for you. Reborn is designed so that you'll have to try different strategies and line-ups before overcoming the toughest obstacles. All I can tell you is, a balanced team, with offense and defense, multiple typings that cover each other's weaknesses, status moves inflicting burn, paralysis etc. should get you far. As far as mons go, there are a few that you'll definitely want to consider, simply because of how excellent they are: Speed Boost Blaziken, Contrary Serperior, Sheer Force Nidoking, Crobat, Magnezone, Volcarona, Flygon just to name a few. Mons with the ability Sturdy can save you against very strong foes like Pulse mons or Leaders' aces. Focus Sashes too, but as far as I know there are only a couple. Leftovers and Black Sludge can never hurt, provided you have them.
I'm not knowledgeable enough to tell you exactly what TMs and Move Tutors will help you a lot, but as Bafabon very rightly said, try to think outside the box, try new things, and the path to victory will become clear