http://www.pokemon.co.jp/palcity/game/regulation.html
Essentially,
1. Double battles (in DP, Double Cup rules)
2. Lv. 1 - 50
3. No more than one Pokémon of each species
4. No more than one of each item
5. Only items obtainable from RSE, FR/LG, DP, Colosseum, XD and PBR Mystery Gift are permitted.
6. No Soul Dew.
7. Nature Power = Tri Attack, Hidden Power = 30% paralyse, Camouflage = change to Normal-type
8. Only Pokémon obtainable in-game from RSE, FR/LG, DP, Colosseum, XD and PBR Mystery Gift from [HASHTAG]#001[/HASHTAG] - [HASHTAG]#491[/HASHTAG] are permitted, i.e. Mew, Lugia, Ho-Oh, Celebi, Jirachi, Deoxys, Phione, Manaphy, Darkrai are not permitted.
9. Of those obtainable, Mewtwo, Kyogre, Groudon, Rayquaza, Dialga, Palkia, Giratina are not permitted.
10. Dragonite and Tyranitar, which only evolve at Lv.55, are not permitted.
11. Heatran and Regigigas, which are only obtainable above Lv.50, are not permitted.
12. Only moves that can be learnt by levelling up, TM/HM, breeding, move tutor and special moves on event Pokémon are permitted.
13. A tie is equivalent to a loss for both sides.
14. A loss for both sides will be declared if the battle goes on for too long, at the organiser's discretion.
Essentially,
1. Double battles (in DP, Double Cup rules)
2. Lv. 1 - 50
3. No more than one Pokémon of each species
4. No more than one of each item
5. Only items obtainable from RSE, FR/LG, DP, Colosseum, XD and PBR Mystery Gift are permitted.
6. No Soul Dew.
7. Nature Power = Tri Attack, Hidden Power = 30% paralyse, Camouflage = change to Normal-type
8. Only Pokémon obtainable in-game from RSE, FR/LG, DP, Colosseum, XD and PBR Mystery Gift from [HASHTAG]#001[/HASHTAG] - [HASHTAG]#491[/HASHTAG] are permitted, i.e. Mew, Lugia, Ho-Oh, Celebi, Jirachi, Deoxys, Phione, Manaphy, Darkrai are not permitted.
9. Of those obtainable, Mewtwo, Kyogre, Groudon, Rayquaza, Dialga, Palkia, Giratina are not permitted.
10. Dragonite and Tyranitar, which only evolve at Lv.55, are not permitted.
11. Heatran and Regigigas, which are only obtainable above Lv.50, are not permitted.
12. Only moves that can be learnt by levelling up, TM/HM, breeding, move tutor and special moves on event Pokémon are permitted.
13. A tie is equivalent to a loss for both sides.
14. A loss for both sides will be declared if the battle goes on for too long, at the organiser's discretion.