1. Every trainer has smart AI.
2. Starting at level 20, every trainer has Sensible Held Items (Consumable only for Generation 3 games).
3. Every Gym Leader has 6 Pokémon.
4. You may pivot to a new Pokémon about midway through the game, before beating the game, in a specific area designated depending on the game you are playing. Only this Pokémon can beat the game if you choose to pivot.
FireRed/LeafGreen: Fuchsia Safari Zone
Emerald: Lillycove Safari Zone
Heartgold/Soulsilver: Bug Catching Contest (after beating Morty).
   4a. Only Pokémon that have defeated a Gym Leader 
       can enter this area, or otherwise be 
       used for Mid-game pivoting.
   4b. For this "pivot", you may catch 3 (?) Pokémon 
       and compare them. You may level, evo, teach 
       TMs, 
       etc. to any of the 3. You must eventually 
       settle on using ONE of them. You can also catch a 4th (?) Pokémon if they are among your favorites.
5. Every TM can be taught once you pivot, but only once. Before this, only Gym TMs can be taught, and also only once.
6. Every move that boosts an offensive stat more than +1 or boosts an offensive stat along with another one (Bulk Up, Dragon Dance, etc.) is banned. Note how moves such as Agility or Cosmic Power are not included on this list.
7. You can only boost a stat once per battle.
8. If you DO NOT PIVOT, the following will ALSO be banned:
ITEMS: Full Restore, Rare Candy, every X item.
ABILITIES: Huge/Pure Power (unless <411 BST), Speed Boost, Pickup Items (also for pivot?).
MOVES: Absorb, Mega Drain, Giga Drain, Meditate, Howl, Growth, Charge Beam, Drain Punch.


-- GAME SPECIFIC --

FireRed/LeafGreen

1. You need to decide if you pivot or not once you reach Fuchsia City.
2. Misty must be fought right after you beat the Rocket that gives you a Nugget on the Nugget Bridge.
3. Lt. Surge must be defeated right after you receive Cut.
4. IF YOU DO NOT PIVOT, SS Anne optionals and items are banned.
5. Erika's Gym must be completed before entering Rocket Hideout.
6. IF YOU DO NOT PIVOT, the Sevii Islands are banned. They are accessible if you pivot, with some restrictions:
6a. Treat this place like a dungeon.
6b. Only the Full Restore and Iapapa Berry items are allowed. Any other item from this place is banned.
6c. Only Island Three trainers are allowed.