Your mother. I'm serious guys. So, you beat the Elite Four. You've wondered why your rival chose the starter weak to yours. As you march into the Champion's room, ready to duel with them... "Hello, sweetie!" And it's your mother. So her team is actually competitive, and she got the starter strong to yours.
What if Ash or Red? Or Rival. Like you think he is bad for so long, and he is like "but you can't beat real team."