“I serve… a higher authority…”
Geno (whose real but "hard to pronounce" name is ♡♪!?) is a warrior from Star Road and one of Mario's partners in Super Mario RPG: Legend of the Seven Stars. He is sent by "a higher authority" to restore peace to Mario's world. Although he takes the form of a wooden doll, Geno is presumably a star being.
 Super Mario RPG: Legend of the Seven Stars
When Smithy launches his attack on Mushroom World, he decides to make Bowser's Keep his base of operations. Thus Exor, the dimensional gateway to Smithy's world, crashes into the castle and occupies it. However, as Exor fell from the sky, he shatters the Star Road. As a result, seven Star Pieces are scattered throughout Mushroom World. With the Star Road broken, wishes cannot be granted. Because of this, Geno is sent to retrieve the Star Pieces and restore the power of wishes to the world.
Some time later, Rose Town is besieged by the Smithy Gang. Bowyer, one of Smithy's lieutenants, is launching arrows into the small town and paralyzing people. As a result, the people of Rose Town cannot leave their homes for fear of being paralyzed by one of Bowyer's arrows.
During this time of crisis, Mario and Mallow arrive in Rose Town. Seeking shelter from the arrows, the pair enters the town inn. Inside, Mario sees a young boy named Gaz playing with his dolls of Mario, Peach, and Bowser. He is recreating one of Mario's various adventures. Gaz's mom, who is also the innkeeper, asked the plumber to play with her son. Gaz pretends to be Mario, and Mario pretends to be Bowser. During the pretend battle, the Mario Doll "bought the farm," so Gaz brings his newest doll: Geno. However, Gaz plays a little too rough. He activated Geno's "Super Star Shot" and instead of hitting the Bowser Doll, the blast inadvertently hits Mario, knocking him out.
That night, a single star being, the one later known as Geno, enters the Inn. Seeing the four dolls on the floor, the star decides to inhabit the Geno doll. Later, Geno admits he chose that particular doll because it appears to be the strongest of the four.
The next morning, Gaz tells his mom that he saw a living Geno walk into the Forest Maze. Because of this, Gaz receives a time out from his mother for telling a lie (which, of course, isn't). Mario believes the kid's tale and enters the woods to find the animated doll. Eventually, Mario catches up with him. Geno enters the forest to challenge Bowyer, the arrow-firing fiend, and retrieves the Star Piece that Bowyer discovers. Mario and Mallow decide to help Geno, and together, the three defeat Bowyer and acquire the Star Piece.
After defeating Bowyer, Geno realizes he needs help recovering the remaining Star Pieces and decides to join forces with Mario and Mallow. Geno reveals to the heroes that he is a warrior from Star Road and that he assumes the form of a doll to fight the Smithy Gang. Additionally, he states that until all the Star Pieces are recovered, wishes can never come true again. He also reveals his real name, ♥♪!?. However, this is impossible to pronounce, so the star warrior assumes the name of the doll: Geno.
Eventually, Mario, Mallow, Geno, Bowser, and Toadstool collect the remaining Star Pieces and defeat the maniacal Smithy. With Smithy destroyed, Geno decides to leave the doll's wooden body, returning to the form of a star and bringing the Star Pieces to Star Road. Repairing the celestial road, the power of wishes return to the world. The lifeless Geno doll can be seen sitting behind Mario and company on Vista Hill while they witness Exor disintegrate.
 Mario & Luigi: Superstar Saga
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.
 Character Description
Geno acts as a sage-like figure to Mario and his allies. He has an understanding of the bigger picture and the greater consequences of cosmic events. Consequently, Geno offers the heroes advice about matters the others may not understand. For instance, after Mario and his allies liberate Bowser's Keep, Bowser decides to quit the team and return to the castle. However, Geno points out that until Smithy and his factory are destroyed, Bowser's Keep is still at risk. Thus Bowser decides to continue the fight.
Geno has a variety of attacks which use a mix of physical and energy projectiles. His regular attack involves shooting physical projectiles from his arms. His special attacks typically involve powerful energy blasts. Additionally, Geno is the fastest of Mario's allies.
Geno's personality is strongly based on his confidence and attitude. Quite different from that of Bowser's, which mostly comes from his tough guy ego and narcissistic traits, Geno has more of a defiant, heroic attitude which is evident when the party confronts Smithy and Geno yells "Yo, Smithy!" upon making his appearance. His eagerness to confront the villain may be due to his status as an authority figure from Star Road.
Geno also tends to show more enthusiasm than any other party member, perhaps only second to Mario, but it is difficult to tell as Mario is a silent protagonist throughout the game. Geno's rhapsodic ways may also be because he knew what the Smithy Gang was up to long before anyone else in the party or in the game does, and living in Star Road, it's close to home.
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, 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.
Despite his strength, Geno perfectly defines the term, "glass cannon". His physical powers are incredible, but his defense, both magical and physical, are the worst in the game and HP is not very high either. Geno does succeed in other areas, though. His speed trumps Mario and his strength exceeds Bowser, making Geno the party's likely assassin, good for taking out difficult enemies early in the round. When equipped with the Feather, Geno is the only character able of defeating a Shy Ranger(provided Mario doesn't the Super Suit + Attack Scarf combination). Except for Geno Boost, a support move, Geno's special moves largely revolve around single and multiple enemy attacks. Most of his magic is difficult to execute perfectly, however. Geno's power begins to deteriorate late-game, unfortunately, as his ultimate weapon, the Star Gun, is not nearly as powerful as others, such as Mario's, the Lazy Shell.
 Special Moves
 Initial Stats in Super Mario RPG: Legend of the Seven Stars
 Names in Other Languages