A few questions regarding damage reducing berries?

Question

This is Smogon's description of damage reducing berries

Halves damage taken from a supereffective (enter type name) attack. Single use.

1) So, what will happen if the berry is held by a Pokemon who does not take super effective damage from the berry's type. For example, what will happen if Mew (A Psychic Type) holds a Chople Berry (Reducing Fighting type damage). Will it reduce damage if Mew is hit by a Fighting type or not?

2) This is specifically regarding the Colbur Berry (The Dark type one). What will happen if Mew holding a Colbur berry is hit by Knock Off? Will the damage be reduced or not?

Comments

https://pokemondb.net/pokebase/340267/how-does-colbur-berry-work-with-knock-off

This answers the second question not first so I assume it's allowed.

Answer 1

Damage reducing berries only activate on a super effective hit. Hence, Chople Berry won't activate for Mew as fighting isn't super effective to a Psychic type.

To answer your second question:

If used on a Pokémon weak to Dark-type moves holding a Colbur Berry, the Colbur Berry will still be eaten, but Knock Off will get the damage boost regardless.

Source

So, Mew will not take super effective damage but the 1.5x damage still stays.
Hope this helps!