Apparently Trump is an ‘inarticulate orator’, according to iSteve, implying perhaps that Trump is not very smart. I guess Obama could be an articulate orator if habitually using a teleprompter, relying on pre-screened questions, and constantly uttering ‘ums’ and ‘ahs’ in your speech is considered ‘good oration’.
Donald Trump is as articulate as he needs to be to get the necessary votes to win.
His language isn’t perceptibly simpler than the other candidates, unless I suppose you’re paying very close attention.
According to this chart, Trump’s overall language (vocabulary + grammar) is just slightly below average:
Like with G. W. Bush, 95% of voters don’t care if his syntax is off or is his language is too plain. Most won’t even notice, and simplicity helps get the message across.
As for Trump’s intelligence, it’s almost impossible to extrapolate someone’s IQ from their public persona. Nixon in public acted as a populist, but in private was an intellectual. To make an assessment, I would need to know more about Trump’s private life – information such as the type of books he reads, how he talks in private, and most importantly, his formative years. Wikipedia isn’t of much help in this regard.