Even though I'm using a consistent team in my playthrough of the game, my Pokémon are under-leveled.
The level jump when you first get onto Poni Island completely surprised me. I didn't expect the first trainer I would face after a climactic fight to have Pokémon 3 levels higher than that of the climactic battle, or to face wild Pokémon only one level behind said climatic foe. I have some training to do before advancing the plot, because half my team is 4 levels behind the wild Pokémon I'm facing and the other half is 1-2 levels behind.