Is ONE PIECE episode 211 filler?
Canon No, episode 211 of ONE PIECE is canon.
#211
Round 2! Shoot It into the Groggy Ring!
第二回戦！ブチ込めグロッキーリング
Aired 28 Nov 2004
Mochibayo compiled this list from MyAnimeList's labels, because MyAnimeList's episode data is not reaching us at the moment.