Fairly OddParents theory
Every (almost official) time the timeline resets (or branches off).
Abra-Catastrophe (and Deja Vu, more as a joke) - Timmy alone does not have that immense power to reverse things himself. It was the fairyversary muffin that gave him a rule-free wish. He wished Cosmo & Wanda would return, erase the memories, and basically revert to the beginning of the special. This was likely originally planned as a TV movie after Season 2, until Season 3 was announced; thus, it shifted towards the latter.
Channel Chasers - Timmy actually does this thing again, with the combined power of the TV remotes, not just the fairies' wands. He even wished away the TV remotes, thus clearing that timeline. This movie was actually a mid-season finale of Season 4, as School's Out: The Musical is the season finale. However, Season 5 was announced, and that special aired in the summer with that season.
Jimmy Timmy Power Hours - This is where things get complicated for obvious reasons. To sum it up, all crossovers (including Nicktoon Unite and Battle for Volcano Island) happened, as the games strongly imply that Jimmy and Timmy had already met before (JTPH1). Nonetheless, after these events, the worlds got tangled and forced a major reset. However, only Jimmy, Timmy, Cosmo, and Wanda (SpongeBob and Danny Phantom) maintained memories. Nicktoons Dice of Destiny finally hints at this, and Timmy leads the narrative.
Wishiology trilogy - Jorgan and Concil reset everything at the end. They can even wipe memories. There's also a reference to Abra-Catastrophe, which suggests that Timmy can remember the events.
The Past and the Furious - Another time-travel episode; it's also one of the last episodes of Season 9. The next season is another one.
That's all for now.
