Do you guys always accuse others cheating if they're at a higher level at an early part of the game? Man, it's always possible the person was just dedicated to training ya know!
But... That's nothing. Before I reached a gym in the Hoenn Region, I always capture a pair of all possible Pokémon at the time, and level them up to a certain level. (1st gym = 15, 2nd gym =20, 3rd gym = 25, etc.)
You guys have any idea how long that takes???
Eventually, I'd have a pair of each Pokémon at level 60 by the time I reach the Elite Four... (this was on Ruby)