Here's a brand new story, since no one will accept this idea, but 1st, here's the ideas, I don't own Pokémon:

Ash has all of these:

898 Pokémon.

Here's others:

Mega Evolution
Primal Reversion
Bond Phenomenon
Ultra Burst
Dynamax (Gigantamax/Eternamax)
Regional Variants
Gender Differences

All in normal and shiny color.

Of course Goh will have all those too, all in normal color.

Of course here's other ideas for Ash:

Ash is an undefeated champion, every Pokémon League Tournament, every Pokémon League Championship Tournament, every tournament in general, every grand festival, he never lost a battle.

He disbanded every evil organization, he won the world championships, he became Monarch after winning the World Coronation Series, became Grand Duke at the Battle Chateau, won every Battle Frontier, he's even a Pokémon Master, a world champion, and the #1 ranked top coordinator/contest star.

Here's what his companions are:

May, Dawn, and Serena won every grand festival.

Gary Oak is an official Professor.

Leaf is a regional champion.

Misty is an undefeated gym leader.

Brock became a Pokémon doctor.

Tracey Sketchit is Professor Oak's top assistant.

May is also the #1 ranked top coordinator/contest star.

Max is an official gym leader.

Dawn is also the #1 ranked top coordinator/contest star.

Iris is a Dragon Master and a regional champion.

Cilan is a S Class Connoisseur.

Clemont is a successful inventor.

Bonnie is an official gym leader.

Serena is also the #1 ranked top coordinator/contest star.

Lana has caught every water type Pokémon, esp Manaphy.

Kiawe is an official Island Kahuna.

Lillie found her father, and works with her family at Aether Paradise.

Sophocles is an astronaut alongside his cousin.

Mallow has successfully made the family restaurant into a place where people and Pokémon eat at.

Delia Ketchum has opened lots of restaurants in all 8 regions.

Pallet Town becomes an attraction.

Cerise Park becomes the size of 4 football stadiums combined.

Chloe has followed her dreams.

We're still adding Melody, Molly Hale, Verity, Sorrel, Margo, and Risa.

I hope you like these ideas.