One of Phineas's first plans was training monkeys to juggle bicycles (in the Original Story Pitch, a little bit before building the Coolest Coaster Ever). An early activity he participated in was going to a state fair and going on a "lame" roller coaster, which only went up a few feet, then dropped down in and was over after only about 3 seconds ("Rollercoaster").
On the first day of one summer, Phineas built an extremely large rollercoaster, dubbing it the Coolest Coaster Ever. After this, he built a beach in their backyard and remodeled Mount Rushmore for Candace's birthday ("Phineas and Ferb's Quantum Boogaloo", "Rollercoaster", "Lawn Gnome Beach Party of Terror", "Candace Loses Her Head").
Flop Starz
Phineas and his brother perform.
Phineas was famous for a day due to his formation of the band Phineas and the Ferb-Tones, a mega one-hit wonder band. His band included Ferb Fletcher, and Fireside Girls Troop 46231. The band was offered by mega record company Huge-O-Records to be a client, but passed it down a la diva-tantrum. The band performed for the last time at Googolplex Mall, performing Gitchee Gitchee Goo with Phineas's sister, Candace ("Flop Starz").
You know, there's an 'm' in Time Machine
Isabella telling Phineas that there's an "M" in "Time Machine" in 300 Million B.C.
Phineas was one of the first successful time travelers, reconstructing a time machine in the local museum. Traveling to 300 million B.C., Phineas and Ferb were accidentally accompanied by Candace. The time machine was destroyed by a T-Rex, and while Candace completely lost it, the boys took the time to practice patience, and waited for a message Phineas sent to get to the present. After a while, Isabella and her Fireside Girls troop showed up and rescued them. A lightning bolt struck the power cord on the machine, providing enough power for them to return back home ("It's About Time!").
Phineas is responsible for reuniting the band Love Händel for one night in honor of his parents' wedding anniversary. Phineas had no trouble convincing Danny, but needed to convince Bobbi Fabulous and Swampy through song. Eventually, the band finally performed ("Dude, We're Getting the Band Back Together"), and it seems they have stayed together, as they were featured in several episodes afterwards as well.
Phineas and Ferb in their space suits
Phineas and Ferb mount to the rocket, with Perry in Phineas's arm.
Phineas and his step-brother went into space, in order for them to see a star that their father named after them. Their sister accidentally tagged along, and the three went on a perilous journey through the galaxy. Surviving an asteroid field and other dangers, they ran out of fuel and stopped at an asteroid where a milkshake bar stood. There, Phineas and Ferb found out that it was really a star and that they owned it. After a while, they returned home, where Phineas was asked to go to a dance by Isabella. And he accepted stating that he and Ferb will see her there, because he didn't realize she meant a date with just the two of them ("Out to Launch").
As the middle months approached, Phineas and his friends formed Aglet Aid to raise awareness for Phineas's new found joy, aglets. The aid proved successful, and raised awareness all through Danville. A concert raised bigger awareness, but all memory of the day was erased thanks to Heinz Doofenshmirtz ("Tip of the Day").
Nosey out of zinc
Phineas (center) with Ferb and a withering Nosey.
He and his brother's interest in the creature "Nosey" caused them to go searching for it at Lake Nose on their trip there. Riding the boat Nosebud, they eventually found the beast and learned he was a kind and gentle creature, but allowed him to live his life in peace away from the eye of the media ("The Lake Nose Monster").
They as well helped their friend, Baljeet, with building a portal to Mars for his science fair project ("Unfair Science Fair", "Unfair Science Fair Redux (Another Story)").
A few days later, Baljeet asked them for their help with winning a giant watermelon contest. During this time, Heinz Doofenshmirtz caused the entire universe to grow large, but everything seemed normal to Phineas and everyone else, as it did not look different ("Attack of the 50 Foot Sister").
Phineas received a new pet, Goldie. He and Ferb built a backyard aquarium for her, complete with whales, dolphins, and octopi to keep her company. Dr. Doofenshmirtz's creation froze the aquarium, and it was released into the wild after being accidentally (and unknowingly) pushed by Candace ("Backyard Aquarium")
Come home perry14
Jeremy, Buford, Baljeet, Ferb, Phineas and Isabella singing Come home perry
Phineas and Ferb discovered an alien named Meap in their backyard one day. Phineas states that Meap is the one of the most adorable things in the world. When Meap ran off, Phineas went out to search for him with a tracker while Ferb repaired his spaceship. He later revealed to Isabella that he thought she was very cute. They discovered that Meap was really an intergalactic security agent, and helped him defeat his nemesis, Mitch ("The Chronicles of Meap").
One night, while Phineas and Ferb are sleeping, Perry disappears into his lair and is told by Major Monogram that he will be assigned to a new villain, and also, a new family. Perry then leaves the following morning, leaving Phineas in a state of depression and sadness. Phineas decides to host an awareness campaign (much like he did for the aglets) and sings a song about Perry. Perry then arrives, cheering Phineas up automatically ("Oh, There You Are, Perry").
Phineas, Ferb, Candace, their parents, and Isabella get shipwrecked on a deserted island after a storm. Lawrence asks Phineas and Ferb to help build a shelter where they can stay inside, and Phineas and Ferb do so. However, they overdo it and instead makes some sort of vacation home. Despite that they were only doing what their dad said, Candace tries to bust them (the only reason being that she's angry they didn't build something that would reach the mainland).("Swiss Family Phineas")
On a visit to the beach, Phineas, Ferb, Isabella, Baljeet, Buford, and their uninvited "friend", Irving goes out to look for the lost city of Atlantis ("Atlantis").
On Tri-State Area Unification Day, Phineas and his friends decides to hijack the parade to show what Tri-State unification is all about, making giant floats of themselves, and even have Love Händel perform. Buford makes several attempts to interrupt the parade, but Phineas took precautions and managed to escape his traps. After the floats had literally floated away, Phineas and his friends continues the parade by simply pulling wagons ("Hip Hip Parade").
Upon realizing that their skate track would be too dangerous to complete without a specialized suit, Phineas and Ferb decide to construct a suit that would aid in survival in the completion of the skate track. After completing the track, the two suddenly hear a call for help and are dragged into being Danville's superheroes, the Beak. They find themselves engaged against Khaka Peü Peü over the possibility of either the best or worst day ever. After a series of battles, the boys reveal their true identity after realizing that Khaka Peü Peü had never had a best day ever. Soon after, Khaka Peü Peü is forced away by his wife and the boys and everyone else head home for snacks. ("The Beak")
When Linda agrees to become part of the 80's Reunion Concert, Lawrance becomes worried and reluctant. In order to put Lawrance at the same level as Linda, Phineas and Ferb decide to make him into a used-to-be famous singer. ("Ladies and Gentlemen, Meet Max Modem!")
On the day of Phineas's birth, Isabella, Baljeet, and Buford compile a series of their favorite moments with Phineas. All the while, Phineas embarks on a scavenger hunt. ("Phineas' Birthday Clip-O-Rama!")
Inspired by the outdated effects of the magic carpet ride scene in The Pinhead Pierre Show!, Phineas and Ferb decide to make their own version of a magic carpet ride. ("Magic Carpet Ride")
Adult life
In the 2020s, twenty years after they built the Coolest Coaster Ever, Phineas had earned an award that was presented to him in Switzerland. Prior to that, either he or Ferb married Isabella, as she was introduced to Candace's future children as "Aunt Isabella". Which of the two married her was not stated ("Phineas and Ferb's Quantum Boogaloo"). The adult version of him was never seen but was mentioned, like Ferb's adult version.
Personality