I also want to check: do you want this team to be OU legal, or are you interested in advice to dominate wi-fi? Other people are no doubt going to sweep by with great advice, but I'll focus on some basics I think you could toss into your game without too much difficulty.
The first thing I'd suggest is losing the Focus Sash on Mamoswine: you've got a lot of physical attacks there, so maybe a Choice Band might be the better choice. (See what I did there?) I'd also go with an Adamant Nature. This is assuming you want to make it more of a physical attacker than a dedicated lead, but you'd want something else to replace it.
If you don't? You could also go Endeavor/Ice Shard, with Stealth Rock, and keep it for a lead.
Regarding Scizor: switch your EVs to 248HP/252Atk/8SpD, to get the most out of it. Aside from that, I don't see a problem. If you decide to replace Mamoswine as your lead, it'll make a great lead for scouting.
I also think you should switch Icy Wind for HP Ice. The extra power more than makes up for the loss of speed, though it does mean you'll have to fix up your IVs: I can understand why you'd opt for Icy Wind in that case. You've still got Mamoswine for coverage, though, assuming you're not keeping him as a lead.
I'd also suggest swapping Focus Blast for Giga Drain, giving your Gengar some recovery - and helping to check Keldeo a bit more, who can fairly easily sweep your team.
That's a start. There's probably more I'd think of if it wasn't so late...