These episodes contain canon material but extend the scenes with anime-only fights or dialogue. They are generally entertaining and do not disrupt the plot.
After finishing the series (Episode 170), you should watch the Netflix original film, Black Clover: Sword of the Wizard King black clover filler list netflix
68, 82, 87, 88, 89, 90, 102, 123, 124, 125, 131, 134, 135, 142, 143, 144, 145, 146, 147, 148 What Can You Safely Skip? These episodes contain canon material but extend the
3, 5–6, 29, 66, 82, 102, 123–125, 153, 157 Anime Canon: 130–152, 154–156 157 Anime Canon: 130–152
Here’s a helpful breakdown regarding the in relation to Netflix (US/International catalog).