I kind of feel like cataloging some good (Don't allow more than one layer of Spikes to go up, don't die) counter-leads to Froslass.
Talonflame: Flare Blitz T1 brings Froslass down to its Sash (and underspeeds T1 Destiny Bond), T2 it can pick Froslass off with Brave Bird before it moves.
CB Tyranitar: 252+ Banded Pursuit drops Froslass to Sandstorm range even if it doesn't switch. If it does, Tyranitar's sand KOs it when it switches back in.
Mega Sableye: Spikes are bounced back, Mega Sableye walls Froslass, Froslass eventually dies (probably to Burn damage).
Weavile: Even without Moxie, it can still click Knock Off T1 and Ice Shard Froslass out of the way T2.
Entei: A 50% chance to burn its way through Froslass's Focus Sash on T1 is great, but it's not as reliable as the others.
Magic Coat is cool for forcing Froslass out, but doesn't actually pose a threat to it. Everything else I can think of is booped by Ice Beam (Thundurus, Mega Absol) or lets too many Spikes get up or has to play games with Destiny Bond.
Talonflame: Flare Blitz T1 brings Froslass down to its Sash (and underspeeds T1 Destiny Bond), T2 it can pick Froslass off with Brave Bird before it moves.
CB Tyranitar: 252+ Banded Pursuit drops Froslass to Sandstorm range even if it doesn't switch. If it does, Tyranitar's sand KOs it when it switches back in.
Mega Sableye: Spikes are bounced back, Mega Sableye walls Froslass, Froslass eventually dies (probably to Burn damage).
Weavile: Even without Moxie, it can still click Knock Off T1 and Ice Shard Froslass out of the way T2.
Entei: A 50% chance to burn its way through Froslass's Focus Sash on T1 is great, but it's not as reliable as the others.
Magic Coat is cool for forcing Froslass out, but doesn't actually pose a threat to it. Everything else I can think of is booped by Ice Beam (Thundurus, Mega Absol) or lets too many Spikes get up or has to play games with Destiny Bond.