Welcome to KpKomedy51's Canon!
Welcome to this quick "update" which sort of explains the canon of current and upcoming stories.
Flash Forward:
Everything that happens in the series is canon and this story takes place roughly 20-30 years after Season 3.
Unfinished Business:
With the exclusion of "The Origins: Part One" and "The Origins: Part Two", none of the events of the series have occurred and will not occur at all. Carrie's dad is not dead in this timeline, Anais and Billy met much earlier in this timeline, the Wattersons live in East Richwood, California a town near Elmore, Anais and Darwin attend Evergreen Elementary School as 4th graders, and Gumball attends East Richwood Middle School as a 6th grader. Gumball is also smarter in this timeline.
Rain of Shrapnel:
All events of the series are canon up to the Season 3 episode "The Safety" where Darwin takes over Elmore and actually succeeds in world domination.
Ninja George Saga:
All events of the series are canon up to the Season 4 episode "The Bus" and Gumball and Darwin get the chance to make "Ninja George" (from the Season 2 episode, "The Tape") into an actual movie. The events of the Season 3 episode, "The Oracle" also don't happen in this timeline and Banana Barbara doesn't have the ability to see the future.