The only berries that are good on cofagrigus are colbur for knock off users and chesto on rest iron defense sets. However, cofagrigus isn’t a good Pokémon and is outclassed as a defensive ghost type by galarian corsola. I’m pretty sure Mimikyu’s EVs don’t do anything. Drain punch should be replaced by play rough so that mimikyu can do more to dark types, which otherwise match up pretty well against ghost teams. Dusknoir is bad, if you want a slow and powerful wall breaker you should use alolan marowak. Spiritomb isn’t good either, Shadow ball + dark pulse is a bad combination because dark pulse doesn’t cover anything shadow ball does except for normal types, which are dealt with by focus blast, which is better than dazzling gleam.