Here, I'm going to give some of Mario's most intelligent intelligence feats and I'm going to explain the context of them. Most people seem to think Mario is at best a genius, but I'm going to give my clause on that.
He is stated to have the knowledge of a physicist and is also a professional doctor. He's been compared to an archaeologist in the manual of SMB3. Most people see these things and believe this to be the zenith of Mario's intellect. In actuality, these are just minor intelligence feats and titles to just say "Mario is intelligent", and they don't pin him down to these levels. He also outsmarted archaeologists and scientists during his vacation to Pi'illo Island, solving the very mystery that left the aforementioned people scratching their heads, so we know he is smarter than just beings with those titles, so we shouldn't pin him down to that extent.
Over time, he can successfully translate Yoshi language, Chain Chomp language and even Shroob language. Looking at the context of all of these, we know that he should learn the Yoshi language, sure. He has spent his entire life with Yoshi's. It's still impressive, considering nothing suggests Yoshi's tried to teach it to him or anything. Chain Chomp language is far more impressive. Even though he's spent a large portion of time fighting Chain Chomps, he still almost never interacts with them other than fighting, and so he just happens to be able to understand them from mere utterances that they've given during combat. And the Shroobs have only ever fought him. To put it simply, he was able to understand a complex dead language after only hearing a few phrases of it during combat with Shroobs over the course of a few days worth of time.
Built a fully functional submarine out of nothing but a bathtub and water pipes. Also created a hat that works as a fall-out shelter. Also made a time machine out of a barrel that can target people across time. It's hard enough to build a submarine, but he's doing it out of just a bathtub and pipes. Where did the glass even come from? He also did it in a short amount of time. Making a hat into something that can withstand nukes, making cloth be able to withstand City level explosions and heat hotter than the Sun and immense radiation, it's really impressive. And then the time machine, he made out of only a barrel. He did this quickly, and also made it to where this time machine can sniff people throughout different points in time, and also can hurt people with High Multiversal+ durability.
He is also smarter than Bowser, who has done immensely incredible things, like creating an entire functional space station that still operates beside the Sun, building an enormous battle mech, building a dark matter plant and dozens more reactors, has been stated to have an I.Q. of 9,800, and finally, creating a castle, a military consisting of ground forces, a navy, and an air force, said military being revered for its strength across all the worlds in SMB3; which as proven much further above, are all universes. Before claiming hyperbole on the I.Q. thing, let's check the context; in that part of the game, Bowser built an entire Science laboratory and created a monster using nothing but excess chemical mixtures; the entire mini-game is trying its hardest to stress that Bowser's a smart character, and combined with all those other feats, it's hard to doubt such a statement. Nintendo also considers an Alakazam to have an IQ almost half of Bowser's, even though its brain cells multiply infinitely, and it never forgets anything it learns, and it is said to know everything that has ever happened in the world. He is also capable of kidnapping Peach consistently, even though she literally can nullify his magic.
His combat skills are just as impeccable. Mario has hundreds of years of combat experience as we know from him attending many Star Festivals that only occur once every hundred years, and spends this time fighting characters with hundreds to tens of billions of years of combat experience such as Dark Star, who should be hundreds of years old, Doopliss, the three Shadow Sirens, Cortez, the Shadow Queen, who should all be over a thousand years old, Antasma and Zeekeeper, who should be war veterans that are millions of years old, and even Dimentio, who should near the age of the universe. Mario is also revered as the only hero who could stop Bowser during the events of Paper Mario, even in his nearly dead state at the beginning of the game, which should make him consistently one of the most skilled people in existence alongside fighting the aforementioned people. He has also demonstrated that he can quickly close the gap between him and someone who is more skilled, such as when he defeated Jinx, and during his first battle with the Master, where the master insulted his skill near the beginning of their fight and then ended up getting outskilled. Even when the Master became demonstrably more skilled after their first match, he was unable to catch up with Mario. Mario has fought in very harsh environments, such has over a hundred floors underground, in volcanoes, in many extremely long deserts where the Sun and nature itself is against him, in lightless caves, battles in space next to the Sun, battles in space next to black holes, a collapsing volcano on the Moon, inside of many different surreal and bizarre dream worlds, battles inside of whales and inside of other monsters and inside of Bowser, battles inside Hell where the aforementioned military arsenal was against him, and battles in scenarios where the entirety of all existence, all worlds, and all dimensions are about to cease to exist. With the edition of Super Mario Maker, he has also now went through tens of millions of different levels. Mario has demonstrated many times to be able to combat perfect and even beyond perfect clones of himself, in terms of combat skills, such as Doopliss, who should be Mario with over a thousand years of combat skill, Memory M and Memory M X, who should be an embodiment of Bowser's memories of the combat history of Mario defeating him, and Memory M X being a superior version of that, Shadoo's Mario clone, that was made after she observed him for over 200 fights and removed weaknesses and added strengths, and then Dreamy Mario, who is a clone made to be superior to Mario in every way.
So with all of this, I believe that in both general intelligence and in combat skill, Mario should be considered a Supergenius.