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Damage modification in the Mystery Dungeon series is slightly different from than in the main games due to the differences between the two game engines. Here are a list of differences:
Standard attacks are considered to have no type, and will attack Pokémon of all types equally. Against Wonder Guard, standard attacks will only do 1 damage.
Like the main games, special attacks are affected by types, but in different ways.
In Pokémon Mystery Dungeon: Red Rescue Team and Blue Rescue Team, the type affinities are as follows. Multipliers stack multiplicatively against dual-type Pokémon:
- Super-effective attacks, such as Grass attacks on Water, deal 140% of normal damage.
- Not very effective attacks, such as Fighting on Psychic, deal 70% of normal damage.
- Attacks of little effect, such as Ground attacks on Flying, deal 50% of normal damage.
In Explorers of Time and Explorers of Darkness the multipliers stack in the following manner:
- If an attack is of little effect against one type, the attack is of little effect overall unless the attack is super-effective against the other type, in which case it is not very effective. Thus, Earthquake will do 25% damage against Articuno, but will do 50% against Zapdos.
- There are no additional benefits of double-weaknesses or double-resistances. Thus, a Thunderbolt against Pidgeot (singly weak to Electric attacks) will do as much damage as one against Gyarados (doubly weak) if all other things are considered equal. Similarly, Close Combat will do equal amounts to Weezing (singly resistant) and Yanmega (doubly resistant) if all other things are considered equal.
- Otherwise, they stack as in the main games.
The damage multipliers are then calculated from the net result:
- Super-effective attacks will do 70% more damage from special attacks.
- Not very effective attacks will do 50% damage from special attacks.
- Attacks of little effect will do 25% damage from special attacks.
Note that type affinity changes brought forth by moves or abilities do not use the above - Levitate will still render Ground attacks useless, for instance.
Critical Hits will only do 50% more damage, unless (in Mystery Dungeon 2) the Pokémon has Sniper, in which case it will do double damage (Sniper, however, will not increase the base power, unlike the main games). Furthermore, in Mystery Dungeon 2, provided that the defender can receive critical hits (i.e. they do not have Battle Armor, Shell Armor, the Lucky Chant status, or the Critical Dodger IQ skill), male or genderless Pokémon will have a 50% less chance of dealing critical hits prior to modifiers (Super Luck, Scope Lens, Patsy Band, the Sharpshooter IQ skill, or the Type-Advantage Master IQ skill). Focus Energy will guarantee that all hits will be criticals while the status is active, provided the defender can receive criticals.