RED

King P - Politoed. Most usually outside its Pokéball.
Douglas - Dugtrio
Norbert - Charizard.
Kanga - Kangaskhan
Mr. Spoon - Alakazam
Jonathan - Hitmonlee

GOLD
Hadouken - Typhlosion
Flying Man - Togetic
Everdred - Haunter
Sonic - Quagsire
Port Town - Furret. Follows GOLD.
Watt - Pikachu. Has a light ball.

BRENDAN
Mr. Fork - Blaziken
Ruflgor - Lickitung. EV trained. Follows BRENDAN.
Dethrai - Lanturn
Portobello - Breloom
Doc - Umbreon
Rick - Altaria. In a Premier Ball. 

LUCAS (sold his Chimchar for something classier. Not very sentimental)
Spectrum - Magneton. Very clean and highly reflective.
Stripe - Rotom (normal form).
MissingNo. - Porygon-Z
Venus - Vaporeon
Mozilla - Ninetales
Escher - Smeargle. Can fly.

BLUE 
Pico - Blastoise
Double A - Electrode
The Tick - Machamp
Benjamin - Mr. Mime
Pythagoras - Rhydon
King - Arcanine

SILVER
Steve - Feraligatr
Mercury - Sneasel
Rex - Tyranitar
Mammoth - Donphan
Zombie - Ariados
Haggy - Misdreavus