Rustle.
You stop from walking, glance around and walk again.
The rustling is louder, closer.
You stop, and look around with wary eyes. "Hello?" Pause.
Turning back, you yelp in surprise to see a Pikachu stuffing your Pokéfood for your Pokémon into its cheeks. It jumps to run away.
It looks lean, despite how many treats it must have taken, obviously a runner. Hmm.. this one might be a little more tricky.
Try to capture?