Well, how about I give you a good format and a team that fit it that would be good.
Format:
1 Fire type
1 Water type
1 Grass type
1 Flying type*
1 Electric type
1 Other **
*- You can substitute Flying with Golurk, because Golurk can learn Fly.
**- I reccomend you use a type not used in your party before. Like if you use Emboar, don't use another Fire or another Fighting type.
This is the basic format I use in every game.
Party:
Fire-Emboar: A good attacker, but watch it's defensive stats.
Water-Carracosta: Has High physical stats, but low speed.
Grass-Whimsicott: Good all around, learns some good moves by TM, great speed.
Flying-Golurk: Awesome attack, learns awesome physical moves, but watch its speed.
Electric-Galvantula: Really good all around, learns good moves.
Other-Krookodile- No bad stats, learns good moves, awesome attack.
Of course, what you do is up to you.