What is the order for watching the Gintama series?
Here is one possible viewing order taken from Gintama Reddit FAQ

What is the watch order of the series?
Skip episodes 1 and 2. They were a special to celebrate the series getting animated.
Gintama: 3-201 (The arc at eps 58-61 was made into a movie. Watch it if you don't care about spoilers, instead of the the arc in the series.)
Gintama Movie 1: Benizakura (the Benizakura arc in eps 58-61). CANON MOVIE
Gintama'(2011): 202-252
Gintama' Enchousen: 253-265 (with some reruns in the middle)
Gintama Movie 2: Be Forever Yorozuya CANON MOVIE. This movie was made to signify the end of the series, as they didn't know if it would continue (but it did).
Gintama° (2015): 266-316
Gintama. (2017): 317-328
Gintama. &quot;Porori&quot;: 329-342
Gintama. Silver Soul Arc: 343-Ongoing
EDIT: Gintama End-Game starts at episode 300. Everything passed there is part of the &quot;conclusion&quot; of the series. Contains heavy spoilers.