Answer by taking a quote from the following article:

Povenmire was born in San Diego, California on September 18, 1963, and grew up in the city of Mobile, Alabama. A child prodigy, he began drawing at age two; by the time he was ten, his work was displayed in local art shows. His first efforts in animation included a series of flip books that he produced in his school text books. As a child, Povenmire considered animator Chuck Jones his hero; in a 2009 interview, he stated that "every drawing he [Jones] did was beautiful to look at and had so much energy in it".

In 1993, Povenmire and Marsh conceived the series Phineas and Ferb, based on their similar experiences of childhood summers spent outdoors. Povenmire spent 14-16 years pitching Phineas and Ferb to several networks. Most rejected it as unfeasible for the complexity of its plots, but Povenmire persevered, later observing "It was really the show we wanted to see: if this was on the air, I'd watch it, and I don't always feel that about every show I work on." Even the Walt Disney Company initially rejected Povenmire's pitch, but asked to keep the proposal packet: "Usually that means they throw it in the trash later," Povenmire recalled. Eventually Disney called Povenmire back with an acceptance, on the condition that he would produce an 11-minute pilot. He called Marsh, who was living in England, to ask him if he would like to work on the pilot; Marsh accepted immediately and moved back to the United States.  Instead of a conventional script, the pair pitched the pilot by recording reels of its storyboard, which Povenmire then mixed and dubbed to produce action and vocals. The network approved the show for a 26-episode season. Povenmire left Family Guy to create the series.  Povenmire and Marsh wanted to incorporate into Phineas and Ferb the kind of humor they had developed in their work on Rocko's Modern Life. They included action sequences and, with Disney's encouragement, featured musical numbers in every episode subsequent to "Flop Starz". Povenmire described the songs as his and Marsh's "jab at immortality", but the pair have earned two Emmy nominations for Phineas and Ferb songs to-date. A third Emmy nomination, for the episode "The Monster of Phineas-n-Ferbenstein" (2008), pitted the show against SpongeBob SquarePants, although neither nominee received the award due to a technicality. In 2010, Povenmire was nominated amongst several other Phineas and Ferb crew members for the Daytime Emmy Award for both "Outstanding Writing in Animation" and "Outstanding Original Song - Children's and Animation" for their work on the show, winning for "Outstanding Writing in Animation".  The distinctive style of the animation legend Tex Avery influenced the show's artistic look. Like Avery, Povermire employed geometric shapes to build both the characters and the background. The style developed almost accidentally, with Povenmire's first sketch of title character, Phineas Flynn, which he produced while eating dinner with his family in a restaurant in South Pasadena, California. He doodled a triangle-shaped child on the butcher paper covering the table. He was so taken with sketch he tore it out, kept it, and used it as the prototype for Phineas and as the stylistic blueprint for the entire show.

What was his role on the show?
Povenmire then mixed and dubbed to produce action and vocals.