One of the fundamental differences between plain concrete and pervious concrete is in the water-cement ratio.
With plain concrete, more than anything the aggregate blend dictates the w/c of a mix. As Walker and Bartel (1947) state it, "...within practical limits, for given aggregates, the quantity of mixing water per unit volume of concrete required to produce a given consistency is the same for any cement content." This is counter-intuitive to what your mother taught you when you were a kid making pizza dough -- if the dough was too dry, add water; too wet, add flour.
Pervious concrete, then, is more like pizza dough. For a given consistency, the cement (cementitious) quantity controls water demand.
I'll use the data from some lab work for the ASTM round robin on surface durability as a example. As the protocol states, three mixes were put up in the lab with voids of 18, 20, and 22%, respectively. Using the same coarse aggregate weight for each mix, the cement contents of the mixes were 655, 602, and 550 pounds, with the corresponding water contents at 216, 199, and 182 pounds per cubic yards. Doing some quick math will tell you that each mix had a w/c of 0.33.
Consistency of these mixes was measured by slump. The same old slump we use for plain concrete -- 3 lifts, 25 rods per lift. Each mix measured a 7-1/2" slump. Of course, we don't know the precision and bias of the slump test for pervious concrete, so this isn't 100% credible. However, the three mixes looked, and behaved very similar. Specifically, blow counts in compacting the specimens ranged from 15 to 20.
For concrete producers, don't get hung up on trying to hit a certain w/c out of concern for quality. Make a mix that works with your raw materials and your customer's equipment -- that will lead to a quality field installation.