You are giving this way more thought than Chris ever did. At the point when Chris originally made those cards he either didn't care about Sonichu's height enough to settle on a number, or he literally didn't bother to change the length and weight from whatever card he based this off of and left it as-is. I'm assuming he did type those numbers himself, and it doesn't make sense because Chris didn't think about it much. "Mah Sonichu is gonna be super tall, and he's really fast so he isn't overweight either so 120 pounds sounds right!".