well as far as your team goes mamoswine looks like the weak link since you are already loaded with physical attackers and Dragonite, conkledur, and scizor are most likely better. Out of what I see on your team Starmie would make the best scarfer since 1) it has a very well rounded move set and 2) it's rare to see a scarf on an already fast pokemon like starmie so you can surprize things like a scarfed flygon who would rock you with a u-turn but instead an ice beam ends his day. Putting a scarf on starmie is easy and worth trying. As for a lead since you're a strong attacking team I would try to set up some hazards to help get OHKO you would otherwise fail to get. I suggest Aerodactyl since it has stealth rock and taunt which is something I love on one pokemon and can be both a lead and anti-lead.