What are the rules for Pokémon Nuzlocke?

I'm planning to do a Pokémon HARDCORE Nuzlocke in HearGold and I'm not too clear about the rules. I'm thinking of playing till the last, that is the battle against Red. Can anyone help me understand the rules?

Also here are some questions that I have about the playthrough- 1. Is trading Pokémon allowed? (Like the Machamp and onix you can get by trading) 2. Gift Pokémon are allowed? (Like Eevee from Bill, Togepi Egg, and the Shuckle) 3. Can you buy Pokémon from the game corner? (It has a Dritini, Abra, which is pretty good addition to the team) 4. Are legendary Pokémon allowed? 5. Is the Laparas allowed which you can get in the cave on Fridays? 6. After defeating Joto, you can play Hoenn and Sinnoh music on Raido to get Pokémon from those regions. Is doing that allowed? And if yes then how will that work? 7. What about swarm encounters you get after defeating Joto? Like Ralts, Swablue, etc. Is that allowed and if yes then how will that work?

These are my questions. Thanks♡