From my understanding it can't cast genjutsu. The only people we've actually seen use the Rinnegan is Pein and Madara. Madara appears to be more skilled with the eyes, since he was the original owner, and was able to pull giant meteors from space. Not saying Nagato couldn't do the same feet but still. Nagato, having the eyes and being an Uzumaki makes him a perfect user for the Rinnegan, since Madara gave them to him, because of his potential. We've seen the Rinnegan have the ability to absorb chakara, repel and attract objects, summon crazy highly destructive animals that have crazy abilities, read minds and rip souls out, bring back the dead, and turns ones body into a mechanoid like being that is really strong and durable. Plus the vision link and others make it the most powerful Dōjutsu in the anime so far. Of course that is just my opinion, but only the sage of six paths probably can use the eyes to their full extent. But of course that's just my opinion... But the rinnegan from our knowledge can't use genjutsu, however, i think it grants the user limited protection against visual genjutsu.. But of course::: THIS IS MY OPINION..
