Steelix = Yes w/, Earthquake/Rock Slide/Explosion/Roar IMOGo for Steelix, because you don't have any kind of tank on your team, and Scizor isn't that good anyway.
Steelix @ Leftovers
Sturdy/Rock Head
- Earthquake
- Rock Slide/Double-Edge
- Rest/Explosion/Toxic/Double-Edge
- Roar
Since this is probably ingame, you can lose Roar and put one of the other options in the last slot. I would say Double Edge with Rock Head, but it's your choice.
While he should probably have a Steelix on his team instead of a Scizor, Scizor is one of the best attackers. It is one of the main bulky attackers in the OU tier, countering Slamence and Dragonite, as well as Scizor being able to do big damage with Bullet punch + Swords dance.Go for Steelix, because you don't have any kind of tank on your team, and Scizor isn't that good anyway.