- Buus aren't very smart, wise, or good looking (penalties to Int, Wis, Cha)
Super Bu is pretty smart despite seeming a brute, quoting TV Tropes:
Bond Villain Stupidity: Averted on every level. Super Buu is very pragmatic in battle and will not hesitate to kill, eat, absorb anyone who gets in his way. The worst thing about it is that he does it with a great amount of surprise. No evil laughing, taunting or mocking. Just straight up death. The only instances he'll every draw out a battle is to discover the weakness of his opponents. When he does find out their weaknesses, he will exploit them to devastating effect. Whether it's flaws in power or personality traits of the opponent.
Although, he was caught somewhat flat-footed when Gotenks revealed he could go Super Saiyan 3 and he was almost killed if the fusion did not break apart when it did. Not to mention, he only escaped from the Time Chamber because he threw a temper tantrum, otherwise he would have been trapped in there forever.
The Chessmaster: No, he seriously was. Super Buu Out-Gambitted everyone in the Majin Buu Arc. And it wasn't just a basic case of Super Buu out smarting them or getting lucky, he covertly came up several plans to become the strongest in the universe and with every plan he came up with, he thought of several back up plans as well. He also manipulated many of the heroes into making himself seem like less of a threat and when the opportunity presented itself from the heroes being arrogant, he would not only take advantage of it but also made sure that there were some contingency plans if things were to go against him. And it worked like a charm, because he technically never loses a battle. And any battle that it seems like he is losing, he's losing on purpose because it's all a part of his plan. It took the Story-Breaker Power of Vegetto just to slow him down. Although in the case of Vegetto, he purposely prolong the battle so he could be absorbed and rescue the others taken by Buu. Otherwise, he would had killed Buu easily.
Dangerously Genre Savvy: Super Buu's surprisingly high intellect and cunning caught a lot of people off-guard in the Buu Arc. Super Buu demanded seeing the "Strong Fighter"/Gotenks (Goten and Trunks fused together) he was promised by Goku, in an effort to buy more time Piccolo suggests that Buu amuse himself by terrorizing the people of Earth, knowing they can be revived with the Dragon Balls. Despite Majin Buu previous rampage there were still billions of humans left on earth so Piccolo thought that with that many humans left it would take Super Buu at least a few hours to fly across the world and terrorize every single one of them. Super Buu instead kills every single human, with the exceptation of Mr Satan, Tien, Chiaotzu and all those present on Kami's Lookout in only two minutes and never left Kami's Lookout while doing it. All of humanity had essentially become a sacrificial lamb for the sake of giving Goten and Trunks just two more of minutes of time to train. It's safe to say that Piccolo's plan of trying to outsmart Super Buu to gain more time backfired on him tremendously.
In stark contrast to other major DBZ villains such as Vegeta, Cell and Freeza, Super Buu goes out of his way to prevent his enemies from getting stronger, even when he's sure their boost won't be enough, just to not take chances. He prefers to just straight up kill them. He does this when Gohan and Goku attempt to fuse, and later when Goku and Vegeta attempt the same.
His reaction when Gohan and Goku try to fuse?
Buutenks: Even if you fuse, you'll be no match for me... but why take the chance? I'll kill you both now!
Manipulative Bastard: Super Buu's surprisingly high intellect and cunning caught a lot of people off-guard in the Buu Arc as he ran rings around the Z-Fighters, making himself look much stupider than he truly was to put the heroes in false sense of security and then strike when they weren't expecting it. It got to the point where he was acting like the The Chessmaster and was playing the Z-Fighters like pawns .
Out-Gambitted
Super Buu out-gambit everyone to the point he could be the trope image. He out-smarted Piccolo by killing everyone in the planet when Piccolo suggested he amuse himself with the survivors to buy more time so Trunks and Goten could train. He used Gotenks' arrogance against him and absorbed him along with Piccolo to create the nearly invincible Super Fusion Buu that wrecked Gohan. When Goku showed up, he made sure they couldn't fuse and when his time ran out with Gotenks, he simply absorbed Gohan, becoming even more powerful. His only real failure was not killing Goku and instead humor him to merge with someone, the only people left were Denda and Mr. Satan. Then again, how could even he predict Vegeta would come back since he died earlier against the much weaker Fat Buu.
Xanatos Speed Chess: Super Buu is very good at doing this, despite being a mere thug in personality. He noticed Gohan's growing power, so he fought against Super Saiyan 3 Gotenks and tested the limits of his strength and his weaknesses (e.g. fusion limit). After briefly fighting Gohan and finding himself overwhelmed, he goes through an intentional Super Power Meltdown, knowing he will regenerate and buys time (and getting Goten and Trunks to recuperate, to fuse again). When he returns he goads Goten and Trunks into fusing again at full power and absorbs Gotenks and Piccolo into his being, deciding 30 minutes is more than enough to handle Gohan (he was right). Goku arrives and the fusion breaks down. Goku says Gohan alone is strong enough to defeat Buu, but then Buu reveals that he planned for this eventuality as well, and had a piece of himself ready to absorb Gohan the whole time, who he goaded into standing still until it was too late. Interestingly, the only character this didn't work on is Vegito, who was too strong, too wily, and had plans of his own, as he later found out...
As you can see, that point is false.
- Absorbing beings of a polar opposite alignment will make the Buu weak (they lose HD/abilities)
Gohan, Gotenks and South Kaio Shin made him stronger (yes, South Kaio Sin making him weaker was a translation mistake, the only one who makes him weaker is the supreme kaio shin, the most common theory is that he somehow sealed part of the power of Majin Boo). False again.
- Food is not really a necessity, more like a drug addiction that can be temporarily solved with a "quick fix." Any being polymorphed into food only solves the hunger and doesn't count as absorption.
Evil Bu absorbed Good Bu this way. False again.