Merciless=When the enemy is poisoned, all damaging moves will be critical hits.
Lucky Chant=Every move the opponent uses cannot be a critical hit.
What occurs if a Merciless Toxapex uses an attack on a Pokémon who is poisoned, but used Lucky Chant? Which move/ability will override?
Lucky Chant will override Merciless, so the critical hits will not be landed.