Ben has multiple showings of being smart with his transformations like against the dragon and literally telling Kevin how to combine his powers as a human. Especially with the Master Control.
People forget Ben is genuinely way smarter than he lets on, especially when his back is up against the wall. Sure, he starts with wrong aliens a lot of the time, but there’s also mistransformations and lack of Master Control holding him back in those instances.
true even he has deeds far beyond a gifted:
Intelligence: Academically gifted, an extraordinary genius in general terms, creativity, and combat. Ben is quite uninterested in school and thus is not particularly worldly at the beginning. This flaw was exacerbated by the fact that he had little interest in studies and preferred to have fun and avoid responsibility, as any kid his age would. However, Ben is constantly cited as being intelligent, quick-thinking, and creative, even by Vilgax, who is known to have defeated the best warriors of ten worlds. Ben managed to face the best warrior of the
Tetramands, keeping up in hand-to-hand combat despite the strength disadvantage and defeating her in Tetramand form. It is said that Ben has a photographic memory for things he is interested in, explaining his occasional inattentiveness. He even says that even when it seems like he’s not paying attention, he actually is, which helped him score 95 on the Plumbers' exams. He immediately figured out that Arditch had the ability to stop his own heart and was pretending to be dead just by
looking.
Ben managed to pilot a technologically advanced spaceship as a child by combining his video game skills with dancing. He defeated Vulkanus, who is so famous for his feats that he has to walk in disguise around the universe because many people try to challenge him to prove their worth, and Crab, who fought in a war so terrible that it caused him to lose all parts of his body. Ben also defeated Vilgax, whose species undergo training from birth, with Vilgax being so feared that he cannot have a crew of organic beings because they are terrified of him.
Ben consistently outwitted Albedo, who in terms of intelligence is comparable to the brainstorm, who could predict every move of the Avengers through mental calculations and analysis. He could even cause problems for Ultimate Albedo, who claimed to be able to predict every possible step Ben would take and that his friends were acting in a specific way within a 100-meter radius. Ultimate Albedo still considered Azmuth's brain superior in intelligence, stating that Azmuth sees the universe "as it truly is," and Ben commented that as the most intelligent being, he should have a thousand plans in mind. However, Azmuth noted that Ben used the Omnitrix in ways he couldn't even imagine, and even with the Omnitrix, Azmuth couldn't defeat Vilgax, something Ben was perfectly capable of.
Ben also defeated R'Ad, who has the ability to read minds and know what his opponent will do. With the Omnitrix, Ben can face beings and even figure out things that not even Professor Paradox, with his absurdly vast experience dealing with threats across space-time, had considered. Ben also defeated Eon, who not only gave Paradox trouble but also killed multiple alternate versions of Ben Tennyson. He learned to use Ascalon in ways that even Sir George couldn't imagine, with Ascalon being such a dangerous weapon that, as superior-level technology, it could cause planetary destruction in the hands of an inferior race.
As a teenager, Ben genuinely tries to study. He scored a C+ in his worst subject, Chemistry, after studying for just a few minutes, probably in the 3 hours he had before the exam started the next morning. Additionally, he becomes a brilliant scientist as an adult, developing his own Omnitrix systems and even fusing multiple aliens for various effects, while nearly single-handedly dealing with crime. At times, he seems lazy and reckless, but he insists that although it may seem that way, he is still paying attention.