Use this snipplet:
IDS = []
class Scene_Battle
alias make_skill_action_result_target_all_later make_skill_action_result
def make_skill_action_result
if IDS.include?(@active_battler.current_action.skill_id)
@target_battlers = []
for enemy in $game_troop.enemies
@target_battlers.push(enemy) if enemy.exist?
end
for actor in $game_party.actors
@target_battlers.push(actor) if not actor.dead?
end
end
make_skill_action_result_target_all_later
end
end
Add IDs of skills that target all enemies and all actors into the IDS = [1, 2, 3] etc. and make them target nobody.