This pokemon is going to be outclassed by Heatran if we are not careful like Aldaron said... With that in mind, I put together a spread of my own. Assuming Special, Mixed and Medium. (The ones currently leading.)
First off is HP. I would like a fairly low HP for better subseeding, but not too low that it dies to Seismic Toss in two or three hits. Not that it would matter, because all this special attacker can do to Blissey is subseed. I'd say that 60 is a pretty good number...
Attack is next. I will figure it out later when I know how many stat points I have to spare.
Defense: As these are balanced defenses, and I want it running with low HP, the defenses are going to need to be fairly high, but not so high as it walls better than Dusknoir. 115 seems like a fair enough number as it is enough that it can take hits but not anywhere near a ton of stuff. Also, my spread is going to be primarily defensive, as I feel this could make a great Tank typing. So 115 it is.
Special Defense: See Defense... Right now it is 115, but I may change it so that it is biased in one way or another.
So just for a recap so far: We have figured out all of the defensive stats so far with 60/115/115 defenses. This leaves us at a 290 total so far. If we are aiming for a spread somewhere in the early-mid 500's. (Since we don't know yet) We have about 250 EV's left to spare between Attack, Special Attack and Speed.
Special Attack: Since this is the main attacking stat, is has to be relatively high, but since I gave it such good defenses, it can't be too good. 100 may seem like a fairly arbitrary number, but it is decent enough to do damage without being too too insane. I may jack it up a bit though.
Speed: I don't have much here to work with, only 60-85, but I'd say it deserves the big end of the stick here with 85, as what I am aiming for is the perfect subseeder. I wish that I had fast to work with, but I don't, so I'll take what I can.
So all that's left is the relatively useless attack, but this may have a chance of have a somewhat usable wall breaking set. I am at 60/?/115/100/115/85 so far which adds up to 475. 65 sounds fair enough, as it has possibility for damage but it far inferior to the Special attack.
That leaves us with 60/65/115/100/115/85 and a BST of 540.
The order is HP, Attack, Defense, Special Attack, Special Defense and Speed.
Seems different enough to Heatran to me, still a little worse though.