Reuniclus can be a Brilliant Wall.
Ability Magic Guard
EVs: 252 HP / 252 Def / 4 SpD
~ Calm Mind
~ Psychic / Psyshock
~ Focus Blast
Calm Mind, of course, is the crux of this set, as it allows Reuniclus to take more hits on its uninvested Special Defense and makes it hit harder. When the opponent begins to put notable damage upon Reuniclus, Recover can heal 50% of its health, which also means there is more time to set up Calm Minds. Psyshock is a decent option over Psychic mainly to defeat Calm Mind Latios and Latias, but it has little utility other than that, as it isn't required to beat special walls such as Blissey. Focus Blast is used to get past Dark- and Steel-types, especially Tyranitar.
So yes IMO when Reuniclus is in play your opponent will not be too happy when he finds out that Reuniclus can take hits whilst using Calm Mind and Recover.