A central element to the Pokémon RPGs is the concept of the Pokémon battle. A Pokémon battle is contested between two teams of Pokémon. There may or may not be restrictions on the size or makeup of these teams. Each battle is essentially a tag-team match, the objective of which is to knock out (or faint) all the members of the other team. To do so, the hit points of the opposing Pokémon must be reduced to zero through attacks.
A battle consists of several rounds. In each round, each side will choose an attack for their active Pokémon. Then, barring special effects from attacks, the faster Pokémon will attack first. If the slower Pokémon remains standing, then it will attack (again, barring special effects from attacks). In some battles, trainers are also permitted to switch Pokémon. As switching is done before any attacks are made, this will allow the other Pokémon to get in a free attack. In the RPGs, a trainer, when battling against a CPU opponent, may also use items that can heal (or otherwise alter the statistics of) Pokémon during a battle. Again, this will allow the opposing Pokémon to get in a free attack. When fighting wild Pokémon, you may also attempt to catch it using a Pokéball. If the catch succeeds, the battle immediately ends, and you acquire a new Pokémon. If the catch fails, the wild Pokémon will attack.
So what is the point of battling? Battling will allow Pokémon to gain effort and experience, both of which contribute to increased overall statistics. Battling is also a method of getting Pokémon to learn new attacks or evolve.
There are 18 types of Pokémon in the RPGs (15 in the first generation of games, and 17 in games before X and Y), with each type having weaknesses, resistances, and immunities to certain types of attacks. If a Pokémon has a weakness to a certain type of attack, the attack is said to be super-effective, and the damage dealt is doubled. If a Pokémon is resistant to a certain type of attack, the attack is said to be not very effective, and the damage dealt is halved. A Pokémon immune to a certain type of attack, of course, receives no damage. These effects are multiplicative, for Pokémon of more than one type. This can mean that a weakness and a resistance will cancel each other out. It can also mean that a Pokémon is doubly-weak or doubly-resistant to a certain type of attack. Because of the fact that only the type of the attack and the type of the defending Pokémon are considered, it is often a good idea to find the combination of attacks that will allow the Pokémon to do super-effective attacks against every type of Pokémon.
There are also attacks that can alter type affinities. For example, attacks such as Foresight remove the immunity of Normal- and Fighting-typed attacks from opposing Ghost Pokémon. In the third generation of games, certain Pokémon may also have abilities that may affect type affinity.
Type affinities for each Pokémon can be found in their Pokédex entry.
However, this does not mean that the type of the attacking Pokémon is a non-factor. If the type of the attack matches any of the types of the Pokémon, then the attack will receive the same-type attack bonus, or STAB, which increases the amount of damage by 10% (50% in the third generation of games). In the second and third generation of games, there are also items that will increase the power of certain attacks. There are also attacks that may have effects on other attacks.
Beware, though, that type affinity is not everything. The statistics of a Pokémon will often determine the strategy to fight with or against it. For example, a Pokémon weak on defense will fall easily to a high-power attack, even if the Pokémon is doubly-resistant to it (or conversely, a weak attacker would have very little chance of taking down a strong defender, even when the defender has a double weakness). Furthermore, the type of the attack will determine which statistics are used in determining the amount of damage inflicted. Dark, Dragon, Electric, Fire, Grass, Ice, Psychic, and Water attacks are considered special attacks, and will use their special attack and special defense statistics to determine the amount of damage done (in the first generation, the special statistic is used for both attacking and defending). All other types of attacks are physical attacks, and will use the physical attack and defense statistics. Thus, a Pokémon may not benefit from high-power attacks when the relevant statistics are very low.
There are three main types of moves: normal attacks, calculated attacks, and non-attacks. Normal attacks use the statics of the Pokémon involved to inflict damage, and is subject to weakness, resistance, STAB, and, in some cases, abilities. Calculated attacks, on the other hand, deal a fixed amount of damage, or damage independent of these factors (but dependent on others). Non-attacks are just that: they deal no damage, but provide some other effect.
Each Pokémon may only have up to four moves at a time, and when a fifth one can be learned, it must take the place of one of the four (alternately, the new attack may be skipped).
Each attack has a certain amount of power points or PP, which determines the amount of times a move can be used. Normally, when a move is made, one PP is used, but when facing Pokémon with the Pressure ability, two PP are consumed. High-power attacks tend to have fewer PP, while lower-power attacks will have more.
In the case where all of a Pokémon's PP are exausted, the Pokémon begins to struggle. Each turn it remains as the active Pokémon, it will do an attack of fixed power with recoil. This attack (Struggle) has no type (rather than Normal), to prevent a match between struggling Ghost Pokémon from going at it forever.
Attacks may also be classified by their effect on Pokémon: some attacks will raise or lower a Pokémon's statistics, while others may inflict status effects. Still, other attacks may have other effects. They can be classified as follows:
- Critical Attacks - these attacks have a higher probability of getting critical hits (see below).
- Statistic Modifiers - these attacks raise or lower a Pokémon's statistics temporarily (for the purposes of battling).
- Status Effect Attacks - these attacks inflict a status effect on a Pokémon, some of which may have consequences outside of battle.
- Two-turn Attacks - these attacks take two turns to execute, and typically hit on the second turn. Some attacks which hit on the second turn give the Pokémon immunity from being hit (except by some attacks) during the first turn.
- Multiple Attacks - these attacks hits as if multiple attacks are made in one turn.
- Recoil Attacks - these attacks deals damage to both the user and opponent.
- Recovery Attacks - these attacks allow Pokémon to recover lost health.
- Switching Attacks - these attacks allow you to either switch opposing Pokémon, or run away from battles against wild Pokémon.
- Suicide Attacks - these attacks knock out your Pokémon.
- Quick/Slow Attacks - these attacks will be performed first (or last), overriding the speed statistics of the Pokémon involved. If two Pokémon use the same type of attack, then the speed statistics are used to determine which attack is performed first.
- Restrictive Attacks - these attacks will trap opponents for several turns, during which the opponent cannot switch (in some cases, attack).
In double battles, introduced with the third generation of games, an attack can also be classified by the Pokémon they hit: some moves attack a specified opponent, some a random opponent, and some may hit both opponents, however, the attack power of the move is cut in half. Some attacks may even hit the Pokémon's partner along with opposing Pokémon.
When a Pokémon attacks with a damaging non-calculated attack, there is a chance that the attack becomes a critical hit. In that case, the amount of damage is doubled, however, any stat reductions/increases are ignored in the third-generation games. The probability of getting a critical hit as follows:
In the first generation of games, the probability of getting a critical hit is dependent on the Pokémon's base speed statistic. It is determined using this formula:
- probability = base speed / 2 * critical modifier / 256 * 100
where integer division is used throughout. The critical modifier is determined as follows:
- Start with 1.
- Multiply by 4 if a critical attack is used.
- Divide by 4 if Focus Energy has been previously used for RBY (yes, this is a bug)
- Multiply by 4 if Focus Energy has been previously used for Stadium
If a random number from 0 to 255 is less than this probability, the attack critical hits.
In the second and third generation of games, the probability of getting a critical hit works on a sliding scale. It works as follows:
- Start at Level 0.
- Move up one level if Focus Energy has been previously used.
- Move up two levels if a critical attack is used.
- Move up one level if Scope Lens is equipped onto the Pokémon.
- Go to Level 2 if Chansey is equipped with Lucky Punch, or if Farfetch'd is equipped with the Stick.
Then, if a random number between 0 and 255 is chosen below the value associated with the level, the move critical hits.