In the series there has been a couple characters who are way more intelligent than anybody else. In my opinion, the candidates for the most intelligent are :
Itachi (planned Sasuke's growth in power and restoration to the Uchiha name; so far he's failed since Sasuke is changing now, it could be considered a success)
Madara (planned the Infinite Tsukiyomi mission, planned his own death and revival using people as his puppets; hasn't succeeded yet but was still revived)
Shikaku (supposed to be the most intelligent man in Konoha until his death; was the "brain" of the alliance)
Shikamaru (always defeats people who are stronger than him by using strategies he makes up on the spot - even when he has no info on them)
(Minato might of been here if we got to see more feats).
Soooo... Who do you think the most intelligent character is?