How does the Pokemon League actually work?

ALRIGHT BUB. You've been messing with me for long enough, it's about time you actually tell me what's up with this whole Pokemon League business.

TIMESTAMPS:
0:00 Intro
How it actually works ----------------
0:54 Generations 1-6
8:10 Generation 7
9:51 Generation 8
13:38 Generation 9
--------------------------------------
17:33 The Issues

Some footage from:
Pikasprey Yellow: (Pokemon Gen 1:    • How to Ruin Lorelei's Pokemon Yellow ...  
   • Sequence Breaking in Pokemon Gen 1  
   • Can You Beat Pokemon Red/Blue With On...  )
Johnstone: (Pokemon Gen 2:    • HOW EASILY CAN YOU COMPLETE PROFESSOR...  
Pokemon Gen 3:    • HOW EASILY CAN YOU COMPLETE PROFESSOR...  
Pokemon Gen 4:    • I Beat Pokemon Platinum Without Gaini...  
   • HOW EASILY CAN YOU GET EVERY GOLD PRI...  
Pokeathlon:    • HOW EASILY CAN YOU GET EVERY POKEATHL...  )
Jrose11: (Pokemon Gen 2:    • Can you beat Pokemon Gold/Silver with...  )
Mixeli: (Sword/Shield Raihan Battle:    • Pokémon Sword & Shield : All Gym Lead...  
Scarlet/Violet Katy Rematch:    • Pokémon Scarlet & Violet - All Gym Le...  
Heartgold/Soulsilver Gym Leaders:    • Pokémon HeartGold & SoulSilver - All ...  
Let's Go Silph Co:    • Pokémon Let's Go Pikachu & Eevee : Al...  
Heartgold/Soulsilver Blue Gym Battle:    • Pokémon HeartGold & SoulSilver - All ...  )
GameXplain: (Pokemon Gen 8:    • All Cutscenes in Pokémon Sword & Shie...  )

Music used:
Clive's Theme - Pokemon Scarlet/Violet (0:10)
Castelia City (NTSC Version) - Pokemon Black 2/White 2 - SiIvaGunner (0:54)
Castelia City - Pokemon Black/White (1:03)
Pokégear Radio: Buena's Password (Beta Mix) - SiIvaGunner (2:16)
Wild Jazz Jungle - Pokemon Azurite (   • Wild Jazz Jungle [Pokémon Azurite OST]  ) (3:51)
Alabaster Icelands 1 - Pokemon Legends: Arceus (5:57)
Gym Leader Battle Theme - Pokemon Scarlet/Violet (6:57)
Ultra Jungle - Pokemon Ultra Sun/Moon (8:10)
Oleana Battle Theme - Pokemon Sword/Shield (9:51)
Klara Battle Theme - Pokemon Sword/Shield (9:54)
Slumbering Weald - Pokemon Sword/Shield (10:50)
Levincia City Theme in the Style of Driftveil City - Me (13:38) (I made it in my free time and liked it a lot, don't judge me)
Montenerva - Pokemon Scarlet/Violet (15:27)
Ryme's Rap Battle - Pokemon Scarlet/Violet (16:44)
Arven's Frustration - Pokemon Scarlet/Violet (17:33)
Cascarrafa - Pokemon Scarlet/Violet (18:13)
Vast Poni Canyon - Pokemon Sun/Moon (20:12)
Virbank City - Pokemon Black 2/White 2 (21:41)