Batcher's special Piercing Howl description would suggest Marked is unresistible.
All Bad Batch allies gain 30% Offense for 2 turns, dispel all buffs and inflict Marked on the target enemy for 2 turns, which can't be resisted. Inflict Ability Block on all enemies inflicted with Off Balance for 1 turn, and Offense Down on all enemies for 2 turns.
The effect descriptions would suggest that the dispel is unresistible but marked is resistible.