Yogg aggro curve is a curve fit for heroes that can get minions for two gold, and don't want to level too fast. Grabbing extra tier 1 pairs, or simply extra economy and strength, before leveling; to be less at risk of losing to a bad shop after leveling.
Heroes with 2 cost heropowers that "buy" a minion can play yogg aggro curve if the tribes and shops are right for it; these heroes include Yogg'Saron, Xyrella, Scabbs. C'Thun often levels on the same curve, though instead of getting extra minions for cheap, C'Thun gets their heropower going more consistently.
Tribes:
Beasts/Murlocs/Elementals for economy on tier 1.
buy or roll heropower
heropower + buy (selling econ unit)
level, heropower
roll, buy and heropower
level, heropower
heropower, sell weakest unit and level