The basic rules for the 2010 Pokémon Video Game Championships have been announced [our emphasis]:
- Players now using Pokémon HeartGold or SoulSilver Version games exclusively
- Pokémon Level 51 and higher being automatically graded down to Level 50 for the duration of the battle using a new auto-leveling feature
- Each Pokémon keeps all of the moves it knew before being adjusted
- Pokémon that evolve after Level 50 don’t devolve
- Any Pokémon below Level 50 will stay at its current level
- Virtually every Pokémon found in the National Pokédex of Pokémon HeartGold and SoulSilver Versions is eligible, including Pokémon traded in from earlier games, with the following exceptions:
- Arceus, Celebi, Darkrai, Deoxys, Jirachi, Manaphy, Mew, Phione, and Shaymin cannot participate
- A team cannot contain more than two of Dialga, Giratina, Groudon, Ho-Oh, Kyogre, Lugia, Mewtwo, Palkia, and Rayquaza during a battle
Players will have to attend local tournaments in order to advance to the World Championships. Participating countries include: Japan, USA & Canada(?), Germany, Spain, Italy, France and the United Kingdom, where Nintendo acts as the direct distributor of their products. Detailed rules are to be announced.
Source: Pokemon.com