Mamoswine is really good in this meta. Adamant CB Mamoswine outspeeds and can OHKO most forms of breloom (jolly max speed breloom is quicker, but most run adamant so in most cases you're quicker), OHKOs Jarooda, Gliscor, Ononokusu, Mence, the three genies, and Sazando with Ice Shard. Icicle Drop OHKOs Dragonite and other threats that weren't taken care of by Ice Shard. Ice shard can also 2HKO doryuzuu, which isn't perfect but when added up with SR, spikes, and LO damage can sometimes kill Doryuzuu. EQ can also help take down some new threats, like Shandera, Roobushin, Blaziken, and most steel types. Stone Edge can take down troublesome pokes like Gyrados. If you want more speed, I'd go with CS, but if you want a more powerful Ice Shard I'd go with CB.