Trump won his party's nomination despite being actively opposed by the GOP Establishment AND most Movement Conservatives. Hillary had to struggle to win her party's nomination even though the Democratic National Committee cleared the field of all Democrats, leaving only an Independent who caucused with the Democrats and was a self-described democratic socialist. Despite all that's transpired, he's only 3 points behind a woman whose march to the Presidency was supposed to be almost automatic.
You tell me who's smarter.
Hillary lacks political talent, but that does not mean that Trump is smarter. I've seen nothing from Trump that indicates a high level of intelligence and sophisticated thinking. He's good at conning people, getting them riled up, and selling his brand. I suppose there is a certain type of intelligence associated with that but overall, I have no doubt that Hillary is smarter.
Trump's nomination was made by possible by multiple factors totally beyond Trump's control. First, the media salivated over the ratings boost from Trump and gave him $2 billion of free coverage, thus drowning out coverage of the many accomplished candidates who ran. Second, the field was highly fractured, with Kasich and Rubio dropping out way past their expiration date. The GOP "establishment" was unable to unify behind a single candidate. Third, the GOP primary delegate allocation rules heavily favor the early frontrunner because beginning on the first Super Tuesday, the states are mostly either winner take all or a hybrid winner take most system; the latter allows the popular vote winner to get the vast majority of delegates. This system is totally different from the Democrats, where every state is proportional, which allows insurgents to win the nomination. The combination of these factors allowed Trump to win. He got super lucky. He is not smart in any meaningful sense.
FWIW, I'm a lifelong conservative Republican and NeverTrump.