I've tried, but I either run into Vaporeon with Heal Bell, Rest, or Hydration (which is only a problem if Abomasnow dies before his Politoed does).
Walrein's an awesome staller, but if Vaporeon keeps cleansing Toxic, he can outstall me, especially if he uses his own Toxic on me.
Does your Walrein not have Substitute?? O_o. Stallrein is faster than standard Vaporeon, and nothing (except HP Electric) will break its Sub. You shouldn't have any problem.