This may have been said already (i'm way too fucking lazy to read 32 pages z_z) but there is one important distinction between cromegabro and crocune: typing.
A psychic typing, while it does give you some nice resistances, isn't really too helpful as it makes you weak to dark, ghost, and bug. Yeah its resistances are kool but that's only really nice when you have partners to cover up your weaknesses and in turn benefit from your resistances (see: heatran, mandibuzz, etc)
However, a "cro" set is more of a stand alone mon. It will, ultimately, take any hit the opposing team has to offer, restalk it all away, and slowly boost up until scald destroys everything. This is where the psychic typing becomes a hindrance: it gives you weaknesses that makes it easier for the opposing team to overwhelm you and thus stop your sweep.
This is where suicune by FAR holds the advantage. Physical grass and electric moves are uncommon, and those two moves as attacking types are rather uncommon themselves. Insane bulk means it can take plenty of hits even from offensive teams, and after 2 calm minds not many special attacks, electric or grass, is really gonna be denting suicune too much. Slowbro has quite a bit more to be worried about however, like knock off's from LO bisharp or shadow balls' from LO gengar or bandzor u-turns/offensive mzor bug bites.
Not only that but its better off sticking to restalk since status just kinda screws it if it runs slack off :/
