Quote Originally Posted by Darth
The Zetsu clones are rather disappointing. You would think they'd at least fight as well as Zetsu himself.

Although, I don't think we've seen Zetsu actually fight yet, so maybe they do.
Madara said that Zetsu isn't suitable for fighting. The only reasons they used him as the original is likely because of his stealth and him actually being clonable. (the latter reason taking the majority of the weight)