To promote Jimmy Neutron: Boy Genius (the movie, not the TV show), a week called "Jimmy Neutron Takes Over Nick" on Nickelodeon started, where they would interrupt several of their shows by switching out the audio or changing it to something entirely else. As of right now, the only found footage is of Jimmy playing fetch with Goddard, a full promo for the movie, a SpongeBob rewind interruption, and a SpongeBob puppet interruption.
Jimmy flipped through many Nickelodeon shows, two in particular being a Hey Arnold episode "Weighing Harold", and a SpongeBob episode "Culture Shock". After which, Jimmy transformed into Carl.
During live action shows, Jimmy would flip the frame upside down.
In the episode "Helga Sleepwalks", Jimmy replayed a scene of Helga eating pork rinds a few times.
Jimmy switched out the audio of a Rugrats episode with dogs barking.
In the episode "Pee-Wee Scouts", instead of interrupting this episode, Jimmy playing fetch with Goddard, now he bites the Nick leaf logo. (FOUND)
In the episode "Squeaky Boots", Jimmy turned SpongeBob and Mr. Krabs into puppets with live-action (à la Cousin Skeeter). It happened again in "Hooky" (featuring Patrick in this episode). (FOUND) 
In the episode "Ripped Pants", he rewinds and fast fowards the episode (including a part where Jimmy laughs to SpongeBob saying "ripped pants" in three times), making it static like a VHS and glitchy voices in the process. (FOUND)
In the episode "Culture Shock", he gives SpongeBob and Squidward his hair.
In the episode "Employee of the Month", Jimmy does the same thing as he did in the Rugrats episode "Pee-Wee Scouts". (FOUND)
In the episode "Blue's Collection", Jimmy switched the episode into a puppet show for 5 minutes and then Goddard switched it back. (existence unconfirmed)
Jimmy flipped the frame upside-down.
Jimmy gives Cat and Dog his hair.
The Fairly OddParents
Timmy, Cosmo, and Wanda go turned into puppets by Jimmy. (existence unconfirmed)
In the episode "Shipwreck Saturday", Jimmy replayed the scene of a boat hitting the toy boat.