I'd suggest you use a fire-flying type, like Moltres because if Mamoswine attempts to use a ground type attack, it wouldn't affect a flying type, plus, with fire type moves like fire blast of fire spin etc, you would wipe the floor with Mamoswine. If you don't have a Moltres, I'd recommend Ho-oh, it's Sacred Fire attack would take Mamoswine to school alright! Or maybe a water type like Feraligatr, Blastoise etc, because water beats ground and it has a normal effect on ice and it's super effective on ground. Plus, both ground and ice type moves have a normal effect on water type pokemon. Or steel type pokemon would do too.