This are the Starter/Trainer pairs I associated with in previous generations (I'm not taking the Anime/Manga/Masters or anything like that into account. These are all just my headcanons for fun)

Kanto
Red - Bulbasaur/Charmander
Blue - Charmander/Squirtle
Leaf - Squirtle

Johto
Ethan - Cyndaquil
Kris/Lyra - Chikorita
Silver - Totodile

Hoenn
May - Torchic/Mudkip
Brendan - Treecko

Sinnoh
Dawn - Piplup
Lucas - Chimchar
Barry - Also Piplup weirdly enough

Unova
Hilda - Tepig
Hilbert - Oshawott
Cheren - Oshawott
Bianca - Snivy
Nate - Tepig
Rosa - Snivy
Hugh - Oshawott

Kalos
Serena - Fenniken
Calem - Froakie/Chespin
Shauna - Chespin

Alola
Elios - Popplio/Litten
Selena - Rowlet
Hau - Rowlet
Kukui - Litten

Galar
Victor - Grookey
Gloria - Sobble
Hop - Scorbunny
Leon - Grookey
For Paldea so far in my head I associate the new starters with:

Florian - Fuecoco
Juliana - Quaxly
Nemona - Sprigatito
Director guy - Quaxly


Before anyone asks, Yes I am very autistic. Not proud of it but it is what it is