Well i had very under leveled Pokemon, that are like level 38-30, the elite 4 was quite difficult, i ran out of potions, and restore stuff, and it was the final battle, and it was a lot easier then the others, which was strange.
The most annoying was in the Ruby, or was it Firered, when you finally got through the exhausting victory road, your about to exit, then BAM! your stupid rival is there to battle, and i forgot to save, and had to go through that process again.