Create a move's secondary effect

Principle

Implementing a move's effect is done in two steps:

• Apply the effect: the deal_effect method executes the effect on valid targets.
• Validate conditions: a verification method determines whether the effect can be applied. This method depends on the move type (offensive or status).

Applying the effect

To define what the move does, override the deal_effect method in the move's class. This method receives the targets that will actually be affected.

Example: Core Enforcer

# Function that deals the effect to the pokemon
# @param user [PFM::PokemonBattler] user of the move
# @param actual_targets [Array<PFM::PokemonBattler>] targets that will be affected by the move
def deal_effect(user, actual_targets)
  actual_targets.each do |target|
    next if target.effects.has?(:ability_suppressed)

    launchers = logic.turn_actions.map(&:launcher)
    next if launchers.first != user

    @logic.ability_change_handler.disable_ability(target, :__undef__, db_symbol, user, self)
    @scene.display_message_and_wait(parse_text_with_pokemon(19, 565, target))
  end
end

• The each loop on actual_targets is mandatory to apply the effect to each target individually.
• next skips to the next target if the conditions are not met for a given target.
• Handlers (ability_change_handler) are used for standard operations (ability change, status, stats, etc.).

Validating conditions

The conditions for applying the effect are checked before its execution. If the conditions are not met, the effect is skipped. The method to use depends on the move type.

For offensive moves

Override the effect_working? method which determines whether the move's secondary effect can be applied.

Example: Core Enforcer

# Test if the effect is working
# @param user [PFM::PokemonBattler] user of the move
# @param actual_targets [Array<PFM::PokemonBattler>] targets that will be affected by the move
# @return [Boolean]
def effect_working?(user, actual_targets)
  return actual_targets.none? { |target| target.effects.has?(:ability_suppressed) }
end

• If the method returns false, deal_effect is not called.
• The check is performed on actual_targets (the targets that were actually hit by the move).

For status moves

Override the move_usable_by_user method which determines whether the move can be launched (see guide 001 for full details).

Example: Gravity

# Function that tests if the user is able to use the move
# @param user [PFM::PokemonBattler] user of the move
# @param targets [Array<PFM::PokemonBattler>] expected targets
# @note Thing that prevents the move from being used should be defined by :move_prevention_user Hook
# @return [Boolean] if the procedure can continue
def move_usable_by_user(user, targets)
  return false unless super
  return show_usage_failure(user) && false if @logic.terrain_effects.has?(:gravity)

  return true
end

• If the method returns false, the move fails entirely (not just the effect).
• The call to super is mandatory to preserve default checks.

Conclusion

• Use deal_effect to implement the move's effect, iterating over actual_targets.
• Use effect_working? to validate conditions for a secondary effect on an offensive move.
• Use move_usable_by_user to validate conditions for a status move (guide 001).
• Use the handlers provided by the system for standard operations (stats, status, ability, etc.).