>>39267461Almost EVERY rival has two starter substitutes.
Green: Exeggutor/Arcanine/Gyarados
Green (Yellow): Cloyster/Magneton/Ninetales
Brendan/May: Shroomish/Numel/Wailmer
Brendan/May (Emerald): Ludicolo/Slugma/Pelipper
Barry: Roserade/Rapidash/Floatzel
Cheren/Bianca/Hugh: Simisage/Simipour/Simisear
Calem/Serena: Vaporeon/Jolteon/Flareon
Hau: Leafeon/Flareon/Vaporeon
Gladion (USUM): Venusaur/Charizard/Blastoise
Trace: Vileplume/Rapidash/Slowbro
In Gen V onward, rivals only use one starter substitute in addition to their starter, while in Gen I-IV, they have two. Trace doesn't have any substitute except his actual starter between versions. But using Eevee's evolutions or the elemental monkeys was always really boring for substitutes. They feel more like placeholders and lack personality. Give Cheren Ferrothorn and Bianca Maractus or something. There's a lot more personality there.