From Bulbapedia, the community-driven Pokémon encyclopedia.
Battling against other human players has been a staple in the games since the beginning, allowing Trainers to pit their teams against each other.
In Generation I
Players can go to any Pokémon Center, to the link counter to initiate battles. Red and Blue set the foundation with straightforward, unrestricted battles with up to six Pokémon per side, with no level restrictions. Items may not be used and choosing to run is equivalent to a forfeit.
Pokémon Yellow introduced several other battle modes, which would also set the stage for Pokémon Stadium.
By using a Transfer Pak with Pokémon Stadium, players can battle each other with full interactivity. Along with no restrictions, players can battle with the Poké Cup, Petit Cup and Prime Cup rules.
In Generation II
Pokémon Gold, Silver and Crystal kept the exact same battle modes as the previous generation, with the exception of held items being used.
Pokémon Stadium 2 also kept many of the same rules, along with the Prime Cup, Poké Cup and Little Cup rules.
In Generation III
Pokémon Ruby, Sapphire, Emerald, FireRed and LeafGreen expanded on the battle arenas with the new Double Battle feature, allowing players to use two Pokémon at once. Players can use the Game Boy Advance Link Cable and the Wireless Adapter (FRLG and E) to link up to four games together, also allowing the Multi Battle. There, two trainers form a tag team against another pair, with each player allowed three Pokémon, each Trainer using one Pokémon at a time to form a pair.
In Generation IV
With the DS wireless communications, Pokémon Diamond and Pearl changed up the battle system. Battles can be fought either in the Union Room or the Communication Club Colosseum. In the Union Room, players need at least two Pokémon that are level 30 or lower.
The Colosseum expanded from Generation III with the addition of Mix Battle, where two Trainers enter with three Pokémon, but each Trainer switches one of their Pokémon with an opponent’s Pokémon. The battle modes are also broken into six cups aside from no restrictions. The Super Cup allows Trainers to use six Pokémon while the Double Cup allows four Pokémon. All the other cups use three Pokémon.
- The Super Cup is unrestricted.
- The Standard Cup sets the upper level limit of a Pokémon to level 50. No two of the same Pokémon species can be used and held items must all be different.
- The Fancy Cup sets the upper level limit to level 30 and the combined team level to 80. Entering Pokémon must be unevolved, be at most six feet tall and weigh at most 44 pounds. No two of the same Pokémon species can be used and held items must all be different.
- The Little Cup sets the upper level limit to level 5. Entering Pokémon must be unevolved. No two of the same Pokémon species can be used and held items must all be different.
- The Light Cup sets the upper level limit to level 50. Entering Pokémon must be unevolved and weight at most 219 pounds. No two of the same Pokémon species can be used and held items must all be different.
- The Double Cup sets the upper level limit to level 50. No two of the same Pokémon species can be used and held items must all be different.
Players can also battle registered friends through Nintendo Wi-Fi Connection by using the Wi-Fi Club. Single and Double battles are available, each with three different divisions: Level 50, Level 100 and Free. In the leveled ones, Pokémon levels will all be set to the chosen category. Free division leaves the levels unaltered.
Pokémon Platinum uses the same rules as Diamond and Pearl.
Pokémon HeartGold and SoulSilver kept most of the same formats. The main exception is the addition of the Flat Battle mode, exclusive to HGSS. Inspired from the Battle Tower from the Generation IV Battle Frontier and DP’s Battle Tower, all Pokémon over level 50 are toned down to that level. Aside from no restrictions, the Light Cup, Standard Cup and Double Cup from the other battle modes are kept. Double No Restrictions is the same as the double battle. The main difference is the GS Cup, where each Trainer uses four Pokémon, with up to two Super Legendary Pokémon per team. These Pokémon are Mewtwo, Lugia, Ho-Oh, Kyogre, Groudon, Rayquaza, Dialga, Palkia and Giratina. The GS Cup will be used in the 2010 Pokémon Video Game World Championships.