Grimlock is an interesting Transformer. He is one of the Dinobots so he is supposed to definitely be stronger than most of the other opponents, but he really only shows this in the G1 continuity. Luckily, one strong version is enough to make this a good fight. Scorponok has been shown to be very powerful in Headmasters though and I would actually give him the edge here. He was able to take on Fortress Maximus after all! Scorponok wins.