He even managed to fight his evil twin Nale with stupidity.
Elan: Nale! You're alive!
Nale: Of course I'm alive, you moron. What I can't figure out is how you didn't know I was alive the whole time. You're the bard, surely you should have known that when a bad guy dies off-screen, he's not really dead unless you see the body. And half the time, not even then.
Elan: Yeah, but the hero always THINKS the bad guy is dead until he shows up again.
Nale: But... If you know that, how can you be surprised... Why didn't you realize that you thinking I was dead was... I mean... Gah! I'm giving myself a migraine just trying to understand the level of willful ignorance that requires!
Elan: First blood: Elan!
Girl Genius has Othar Tryggvassen, Gentleman Adventurer! He has some tendencies towards this trope at times, especially in his own adventures. At one point, he's trying to find and stop the Weasel Queen. He finds a woman with weasel ears and a throne. Conclusion? She must be a Damsel in Distress! Othar is Too Dumb to Live in the Girl Genius world. It's a good thing he's also the Determinator. In the GG comics, Othar isn't The Hero. He's barely A Hero. He's comic relief, and he's dumb to serve the Rule of Funny. In the twitter adventures, Othar is the hero, and he's written as fairly confident and clever, only getting into scrapes because he's a sparky Gentleman Adventurer. (though the twitter is also written byOthar, so take it with a grain of salt). Finally, he's absurdly competent at few things, though. Such as surviving being thrown out of an airship (this happens to him with Running Gag frequency).
Torg from Sluggy Freelance. He Took a Level in Badass as well, and does smart stuff sometimes... but reverts right back. Bun-bun can't decide whether it's an act. The real answer is probably one he has practically given himself: he doesn't like to think and prefers to avoid it. When he actually makes the effort, though, the results are either as good as for anyone else or downright brilliant in a weird kind of way. Though Gwynn thinks "he's smart and knows exactly what he's doing".
Lothar:(after Wildfire's stupidity has ruined their mission New rule: No member of the team is allowed more beam swords than brain cells.
She was so stupid, The team had her chloroformed, passed of as injured (complete with full body cast), and sent back to Taika in exchange for Rogue, who they, after what Wildfire's done, are delighted to see.
John does have hidden depths, but he still plays this pretty straight most of the time. He's pretty gullible (having been lead to his death at least once), wastes time reenacting inane scenes from terrible movies, generally has far less clue about what's going on than the other characters... but is the first human to ascend to God Tier, and is capable of using The Windy Thing to produce tornadoes so strong they can drill through the planet. He seems to be heading toward the All-Loving Hero. He considers himself the other kids' friend rather than their leader, which (as Rose points out) is precisely why the other kids consider him their leader.