Slippy is the son of Beltino Toad, the Research Director for the Cornerian Defense Force. Slippy and Beltino invented and constructed many inventions for the team, including the Blue Marine. In the gap between Star Fox 64 and Star Fox Adventures, Slippy and his father briefly designed aircraft for Cornerian defense forces. He is hinted at being less athletic than the rest of the team, an example being in the ending of Star Fox 64, when the team runs a long distance, Slippy slowly falls behind and, in the introduction of the same game, he is seen falling behind his wingmates. Also, in Star Fox Assault, in the scene where everybody jumps into their Arwings for launching, Slippy ends up falling head first into his ship.
Slippy played a major role in the Lylat Wars as a new (and barely experienced) pilot of the Arwing. His main role was to give information about the area (in a similar way that Peppy does) and to analyze the shield strength of bosses. Slippy's inexperience and lack of talent while flying get him into trouble more often than any other team member, for which Falco taunts him mercilessly. During dogfights between Star Fox and Star Wolf, Slippy shares a rivalry with Andrew Oikonny, although there has never been anything to suggest the two characters have a history, and there is little dialogue between them.
Slippy was sent to Captain Shear's base to investigate anything about him, after the Star Fox team learned some facts (like Falco apparently siding with the Androssian rebels) that do not make any sense. Unfortunately, Captain Shears realized that Star Fox failed to stop the Hot Rodders (the group he claimed were Androssian rebels) so he dispatched the Golas to kidnap anyone who tried to come near the base. Slippy was also uncomfortable with going to the base, as he has bad memories of the last time he was on Titania. He was later saved by Fox and tried to halt Andross's revival, but only succeeded in quickening it.
Slippy also helped out in the Sauria crisis. Instead of flying, he had stuck with giving Fox information and helpful hints about his surroundings. During the long 8 years between the Lylat Wars and the incident on Sauria, Slippy withdrew from active flight duty so he could spend more time working on his developments, one such design was a Sharp Claw disguise which enabled Fox to fool the Sharpclaw and access various areas. When Andross was defeated again and Falco returned, Slippy happily recited: "The Star Fox Team is back together again.", showing his appreciation of Falco. Slippy also gladly accepted Krystal into the team as well.
Slippy played a role in the Aparoid invasion similar to his role in the Lylat Wars. Back in an Arwing, Slippy provides shield analysis data on exceptionally strong enemies and occasionally comments on certain technological aspects of the stages or gives hints about special devices or weapons, although not as much as Peppy. Slippy's skill with the Arwing has improved little, if at all, and is still teased by Falco.
After the Aparoid race was destroyed in Star Fox Assault, Slippy temporarily withdrew from the Star Fox team to spend more time with his newfound love, Amanda. However, when Fox needs backup taking out the Anglarforces, Slippy is happy to come to his assistance again. He pilots the Bullfrog (ブルフロッグ), which has Plasma Lasers and high shielding, and is the only ship in the game able to carry up to three Nova Bombs, but has no lock and has only two boost bars. Slippy later marries Amanda and has numerous children, one of which joins the new Star Fox (albiet in another ending).
Super Smash Sisters Role
Slippy is a non-playable character in Super Smash Sisters. In battle, he mostly throws grenades and uses a laser machine gun. He has a few punches and can use a cloaking device to turn himself and his ally invisible. When paired with Krystal or Amanda, they can team final smash.