Search function and pein wins, although its not quiet clear.
What i will say is that there are two or more scenario's to this fight.
The first one being, itachi doesnt know the identity or any of the secrets of those peins and wastes his chakra on them. He would eventually run out and thats his doom.
The second scenario is that he pulls out susano and tries to seal them from the start.
Third scenario he uses tsukuyomi from the start. This should have the same effect as ma and pa's genjutsu because in ma and pa's all of them heard the song and got caught. Pein as its said have shared vision, if this is the case if itachi catches one in tsukuyomi, he catches the rest as well. If this works then he can actually seal them after, because they are there for the taking after eating a tsukuyomi.
Fourth scenario, is that itachi goes straight after nagato and doesnt waste his chakra on the peins. From what we know itachi knows of nagato very well, meaning he already knows pein's secret