I admittedly have little knowledge of youth football, but my understanding is that at ages below 16 or so, they don't allow kids who are way bigger than everyone else to be anything other than linemen.

As far as strategy for stopping the kid. I have no idea. I don't think I'd be happy to let my kid line up on the opposite side of the ball as him if that's what he's going to do to someone who tries to make a tackle.