That's a Munchlax. I have an older version, I can't imagine why they'd have given you that for your starter and not a Growlithe or a Houndour...

[She stops and shakes her head.]

Never mind, I'm babbling. Listen, there should be a red and white ball somewhere in that backpack or on your belt. If you hold that up, you can bring the creature inside it so that it'll stop eating everything it sees. Yes, I know it doesn't look like it should fit, but it's... well, almost a kind of magic, really. Just trust me, okay?