I am up-to-date on every One Piece episode, but I have never watched any of the animated movies.
Are they necessary to watch to understand what happens in the anime/manga?
I am up-to-date on every One Piece episode, but I have never watched any of the animated movies.
Are they necessary to watch to understand what happens in the anime/manga?
One Piece is mainly manga-based. Now, movies do not actually follow the storyline. However, for entertainment purpose, they are ok. By the way, before a movie release, the anime's storyline suddenly does not follow the main (manga's) storyline for at least 3-4 episodes. Those episodes are actually to connect the next movie with the anime's storyline.
So if you want to follow the main story, you may ignore those movies and filler episodes. But for enjoyment, they are good enough. Some of those movies are actually good too.
The conclusion is, the movies are not necessary to follow the storyline.