You'll disagree vehemently I suppose, and not all ID's are Christian and not all Christians are YECs and believe that Noah's Flood is responsible for the fossil layers, but I am and do.
Let's be clear here: you are a creationist and NOT an IDer -- you don't need the ID concept to believe the "Flood is responsible for the fossil layers" AND in fact the ID concept is silent on the question of the flood.
That is the answer from the YEC paradigm -- so far as I understand it.
Exactly, NOT the answer from the ID paradigm.
... (Noah's Flood) -- therefore, there are now fewer body plans whereas there used to be greater diversity.
This is not an explanation from an ID perspective, and in fact is irrelevant and off topic to the issue of whether "intelligent design" can explain these fossils.
The concept of "intelligent design" does not restrict itself to only deselecting species as they dwindle by natural selection, and in fact it posits design causing speciation -- new designs -- all the time.
In it's simple formulation ID really has no conflict with geology or the fossil record