You bump into a Route 1 slut.

You stroll along Route 1, keeping an eye out for any particular girls that interest you. While your distracted looking at the ass of some blonde chick that belongs to another trainer, you accidentally bump straight into a girl who looks a little bit similair to Leaf. The only difference is that instead of having super tiny tits, she just has tits that are smaller than usual, and Leaf's ass is way hotter than this girl. Other than that, this girl's hair is a little longer, she's a little shorter, and she looks just a bit younger.

"Hey there! Looking for somebody to be your girlfriend? How about a cutie like me! A man like you surely will be big and strong, and protect me from those other mean trainers who want to catch me. But you wouldn't let anyone do something like that to a Lass like me, right?"

Honestly, you find her personality rather irritating.

"Tell you what. If you win this battle, you can be my girlfriend and I won't ever try and catch any more girls. And you already know what happens if I win."

"Fine. Be that way. But you'll regret it once I get to show off my new boyfriend to all of my friends!"

"Lass, I challenge you to a battle!"