Playing the game with an underleveled team

So how about you? Do you guys just level up one Pokemon and go for it or what?

Yes. I had to use 3 hyper potions and that was it.

68 Typhlosion, 45 Lugia, 30 Red Gyarados, 3 "Rocky" (the Onix you get from a trade), 3 Bellsprout, 2 Pidgey
I only used Typhlosion. No EV training.