Yeah, in particular Magic Guard Clefable could beat this easily. It can Encore any of Walrein's moves and then spam Thunderbolt which may force Walrein to switch out.
Toxic Spikes will actually help Clefable because it will get Toxiced, but it won't take any damage from it. It also takes no damage from Hail so it will get Leftovers recovery. It's also immune to Stealth Rock/Spikes and will be in tip-top shape to fight Walrein off. It can also take pitiful damage from Walrein's attacks because it has no offense with the EVs you gave it. It'll just shrug off the hit and Softboiled off the damage.
Even if Walrein tries to Roar out Clefable, it will get smacked by a Thunderbolt since Roar will go last. This will do a lot of damage still because you didn't give it any special defense EVs.
I'm gonna go ahead and say that Rock Blast can also counter this seeing as it can bust through the sub with a Super-Effective hit and then do residual damage after it's broken the sub. This means that something like Armaldo may be able to stop it from stalling, as it can knock off the leftovers and use Rock Blast.
On the plus side of this moveset though, Blizzard may be able to make up for the craptastic offenses this spread has, and stealth rock/spikes can be very deadly with this moveset. I do kinda wonder how you plan to deal with special attacks such as Leaf Storm though.
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