Geno's personality is strongly based on his confidence and attitude. Geno has more of a defiant, heroic attitude. His eagerness to confront the villain may be due to his status as an authority figure from Star Road. He also tends to show more enthusiasm than any other party member. Geno comes off as very powerful from his first appearance as a doll when Gaz attacks using Geno and accidentally hits Mario and knocks him out. However, when Geno tries to fight Bowyer, upon striking Bowyer will say, "Strong you are, but stronger am I!" One of Geno's magic powers is also potentially the most powerful attack in game, Geno Whirl. If timed just right, it deals 9,999 points of damage; if not timed right, it does average damage at best. The skill works only on regular enemies, as well as Yaridovich, Machine Made, and Exor. Although powerful, Geno is quite amiable, quick to make friends with Mario and Mallow. He has a strong sense of duty and responsibility, and his role on Star Road may be analogous to Mario's role in the Mushroom Kingdom. He even worries over the "ownership" of his physical form, and promises to return the body to the home from whence it came.
Geno's doll form makes a cameo in Mario & Luigi: Superstar Saga. He appears as the mechanical host of the Star 'Stache Smash arcade game in Little Fungitown, explaining the rules of the minigame. Geno appears in the Super Mario RPG: Legend of the Seven Stars volume of the Super Mario-Kun manga. Being an adaption with a few tweaks, he fills the same role as he did in the game.