Kingdra is an interesting defensive option with an amazing typing. It sacrifices attack for 150/95/95 defenses, while it's special attack remains untouched.
Kyurem drops it relatively unused Attack stat to gain some extra defenses.
Regigigas drops attack for a massive special attack stat that doesn't get dropped by slow start.
Meloetta Aria drops special defense to get massive mixed attacking stats, sadly, Pirouette is pretty bad now.
Articuno gets a massive attack stat in exchange for defense.
Omastar is a beast in rain.
Carracosta has an epic shell smash set losing unused defense to get enough speed to actually outspeed things at +2.
Leavanny becomes a great specially defensive sticky web setter.
Huntail is legitimately scary as hell. Crustle is buffed too.
Magneton is a decent Eviolite user with comparable defense to Pory2.
Clefable is still a solid defensive pivot, but now with speed and les offense.
Rose is the same.
Banette is a pretty awesome defensive prankster.
Specially defensive Mega-Saur is legit crazy.
Mega-dos can use that epic special movepool.
Mega-Dactyl is a great Assault vest user.
Mega-Mawile swaps defense for much needed speed.
Misdreavus is a pretty crazy mixed evi wall.
Greninja becomes a spiker that uses protean to utilise it's solid defense.
Furfrou is a BEAST on the physical side. Like legit. Look at it.
And say hello to Azumarills competition for best drummer in the tier, Slurpuff, who is even faster. (Use both, one to break, the other to sweep.)
Not to mention Barbaracle can mixed sweep.
Tyrantrum has some cool defenses.
And those are the only relevant buffs I can see.
