A Walk in the Park

Lab was a strange Pokemon. Unlike anything anyone at Cinnabar had ever seen.

I found him on the edge of the water near the gym. He wouldn't let me touch him, but he did follow me home. No one wanted me around after that, though, so they made me leave the island. Eventually, I wound up all the way in Sinnoh.

Lab and I were walking along peacefully when an officer stopped us.
"Little girl," he started, "I don't know what that...thing is that's following you, but whatever it is, it needs to be on a leash. We enforce the leash law around here."
I frowned. "Mister, I can't even touch Lab, how can I put a leash on him?"
"You have the hands to do so. I see you have a leash on hand. Here, let me show you..."

I tried to stop him, but my words weren't faster than the officer's hands. He screamed in pain, pulling back what was left of his arm as he fell to the ground. It was completely gone clean up to the elbow, not a trace of blood or torn cloth. It simply...vanished. The officer wouldn't stop screaming, though.
"Wh-what the hell is that damn thing?!" He demanded. I shrugged.
"I call him Lab. Others call him a monster. But most people only know him by one name."
I stepped back as Lab advanced on the officer, who was starting to cry as it enveloped his lower torso. He was screaming twice as loud, now.

"...MissingNo."