Rate my team: Swampert lvl 78 Rayquaza lvl 72 Groudon lvl 67 Swellow..

Wow! Thats pretty good! It's almost as good as mine! I give it a 8/10. Try to raise your swellow to level 60 and try to get your pikachu to level 55 at least. By the way your Bagon will evolve into a shellgon if you raise it one more level seeing to it that it was supposed to evolve at 30. Try to teach it dragon claw. It's pretty strong and has a lot of pp. Then it evolves into salamance at level 50 and then it learns fly whitch is pretty cool if you ask me. Don't worry about leveling it up because it is extremely easy. If you battle some Pokemon trainers and battle the elite four at least once while it's holding the exp. Share (at the elite four anyway. Actually battle with shellgon during trainer battles) it's really easy. I did it within a day.
If you did all of the above I would give you a 9/10 seeing that your Pokemon arn't at level 100.

By the way heres my pokemon.

Swampert lv.76 (I'm trying to level him up to at least 79)
Rayquaza lv.74
Groudon lv.65
Zangoose lv.57
Salamence lv.50
Snorunt lv.34 (trying to make him evolve)

Your welcome and thanks for putting up with me <

Bagon level up higher then 50

I would say you need some training to do, your Pokemon are all disappointing levels, you will need to keep them leveled up with one another, this way you have a more better fighting chance, I would say work on them all, if you want my opinion.