Just beat the sixth gym. Here's some advice for you
1) DONT USE THE LUCKY EGG FOR IN GAME TRAINING
2) DONT GRIND ON A LOT OF WILD POKEMON AFTER GYM 4
If you do these, the game will become really easy. Too easy in fact. After beating gym 6, my official team is:
Serperior Lv. 37 (After getting Leaf Blade, I really like him now. His movepool NEEDS diversity though. I also wish he was part dragon type)
Stoutland Lv. 34 (I usually don't like using a normal type, but he has a badass mustache and acts as such a solid fighter)
Zebstrika Lv. 38 (He's getting better and better. He would have been perfect if he was part dark, but man is he cool. He has a decent fire move and a great electrical lineup)
Carracosta Lv. 38 (I love Tirtouga, and I love this one, but I wish the design was slightly cooler. He looks like a malnourished Blastoise. His typing and movepool is nothing short of excellent though)
Sawk Lv. 34 (He isn't doing a ton for my team anymore other than being the strength carrier and having good fighting moves, but he is ridiculously solid in battle. He can sweep entire gyms while being underleveled, easily in fact).
Sigilyph Lv. 20 (He has Fly)
I really want to put my new Drilbur in slot 6, but I also need a flying type. Hmm. Does anyone know of a really good flying type this gen I might be missing? I don't really love the peacock basic bird evo. Now that I think of it, I may try to get the swan on GTS