I have often heard members and others claiming a belief in the Bible, say that Satan is very cleaver. But if he was actually all that cleaver why didn't he deceive Moses (Moses 1:12-13)? And why do the Scriptures say that deceiving the very elect won't happen (Matt 24:24)? He wasn't even wise enough to come here and get a body. He has no chance of obtaining godhood.
He was among the first group born (a son of the morning). So he had potential. He had obviously put more effort in as an intelligence to increase himself as an individual, before being born as a spirit child, than most. But his leaning toward greed for power and position doesn't demonstrate very good understanding of the important heart issues. Which would fit in with his going off on false doctrinal concepts like his claim that he could force all to do good, and thus save us.
I would be more inclined to state that Satan presents an idea that we may not have the knowledge to counter. Of course, he may actually beleive that he is right, and be no wiser himself. We may become confused into thinking that what he is presenting makes sense. It is hard for us to admit to being conned by a ninkempoop. So we like to think he must be highly intelligent. And we question how someone could be so apparently successful without having great cunning? But does it take great wisdom for a child to confuse another? Particularly if the new idea seems to offer greater freedom of choices?
Then there are those who just choose evil, because they want to. Satan doesn't need to do much more than make a suggestion, in these cases. Unfortunately Telestials (the majority) are self-first in the main. No great genius required there, by Satan.
Naturally it is his desire to do anything contrary to what God wants. And that of itself demonstrates poor intelligence. A wise person generally won't do something just because someone else doesn't want them to. That makes a person a slave to the other person's ideas (even though the slavery isn't in service).
Look at Satan in Moses 1:19 "And now, when Moses had said these words, Satan cried with a loud voice, and ranted upon the earth, and commanded, saying: I am the Only Begotten, worship me."
And verse 22 "And it came to pass that Satan cried with a loud voice, with weeping, and wailing, and gnashing of teeth; and he departed hence..."
This hardly demonstrates an intelligent being.