Now that I think about it, the Choice Scarf isn't as necessary for Magnezone to fulfill its role of trapping Steels as I thought it was. It loses to Heatran (unless Magnezone is running HP Ground) and Excadrill anyway, Skarmory usually doesn't run Speed investment and it doesn't have any coverage to hit Magnezone, Ferrothorn will never outspeed Magnezone, and not all Scizor run Superpower.