In fact, the first episode says that he was given the personality of a "perfect adult detective", implying that he's been programmed with Gadget's personality and intellect rather than just being Gadget when he was younger.
Badass Adorable: On rare occasions when he's actually competent fighting the bad guys, Gadget Boy can be this.
Spydra: My lovely cold-proof head sack keeps me immune to the uncommon cold!
Boris: (under his breath, to camera) And me immune to her ugly face!
Butt Monkey: Chief Stromboli. Even when Gadget Boy leaves him be, the guy can't go a minute without suffering an accident. Boris the Vulture is also this to some extent. Spydra abuses Boris all the time.
Catchphrase: "Zowzers bowzers!" is Gadget Boy's version of the Inspector's traditional "wowzers!" catchphrase. It's pretty tiresome. On the plus side, he's also prone to quotingMaxwell Smart's "would you believe..." and "missed it by that much."
Creepy Twins: Mulch and Hummus, Spydra's none-too-bright henchmen.
Expy: Nearly all the characters are an expy of a main Inspector Gadget character: Stromboli is Chief Quimby, Heather is (an older) Penny, G9 is (a robotic) Brain, and Gadget Boy is... well, that's kinda obvious.
Mulch and Hummus even bear somewhat of a close resemblance to some of the recurring M.A.D. agents in Inspector Gadget.
Another episode that had the gang go back in Ancient Greece had Agent Heather go to a sauna for males so she can change and disguise herself as a man to sneak into the first Olympics. We do not see her changing, but we do hear many exclamations from the men in the sauna.
Large Ham: Spydra, who often speaks in alliterative dialogue.
Mad Scientist: Myron Dabble, creator of Gadget Boy. Okay, so he's not really mad, but hey, you've got to have a pretty odd mind to go and create a small child cyborg stuffed with hoard of elecronic equipment.
Monster Mash: In the episode "Gadget-Stein", Spydra goes back to Geneva in 1816 and forces Mary Shelley to create an army of monsters that oddly all resemble Boris the Vulture. The monsters are a werewolf, a skeleton, a centaur, a fat humanoid, a cyclops satyr, a Bride of Frankenstein-esque monster, a gorilla, a mummy, a Loch Ness Monster, and even Frankenstein's Monster himself.