Think of Walrein in UU as Blissey in OU, annoyingly hard to kill, usually takes forever, but dang, we don't get stuff like tyraniboah or McIceGar in UU...
Why complain about Walrein in UU, when there are tons of things that can kill it such as Stantler, Kanga, Granbull. Complaining about a Pokemon being too hard to kill that doesnt have a recovery move(not rest) is stupid. Celebi and Blissey make sense, though Blissey dies to physical attacks, same with walrein. There are no celebi in UU, or anything likeit.