@Carnation1 's Suggestion for a natural rotom line! and I’m happy to provide (because i really have no Ideas right now ;-; )
Delta Rotom (Psychic/Bug)
The Infestation Pokemon
Ability: Compound Eyes
Dex Entry: It’s thought to be surrounded by pure Psychic Energy, It is known to infest materials and become infused with them to cause havoc!
Delta Rotom Lava (Psychic/Fire)
Dex Entry: Delta Rotom Lava exerts all its anger outwards, the more upset it gets the hotter it becomes! In some instances it can begin to melt right through the floor beneath it!
Special Move: Heat Wave
Delta Rotom Snow (Psychic/Ice)
Dex Entry: Delta Rotom Snow constantly is shaping it’s body to intimidate other pokemon, a smart trainer will make sure that its body is always well packed!
Special move: Ice Beam
Delta Rotom Shell (Psychic/Water)
Dex Entry: Delta Rotom Shell spends its time in one place waiting on its prey. It’s flower secretes sweet smelling nectar that draws in other pokemon.
Special Move Muddy Water
Delta Rotom Stump (Psychic/Grass)
Dex Entry: Delta Rotom Stump has complete control of its roots, its very territorial it slowly ingrains itself taking control of the trees and vegetation all around it.
Special Move: Wood Hammer / Ingrain or Giga Drain
Delta Rotom Bumble (Psychic/Flying)
Dex Entry: Delta Rotom Bumble’s body is completely composed of honey at different viscosities, It keeps air in bubble like wings on its back.
Special Move: Fly
So instead of creating another area of the game to use for finding stumps and such, I thought they could use items on the pokemon to change forms, Honey for Bumble, Shell Bell for Shell, Big Root for Stump, Flame Orb for Lava, Icy Rock for Snow, and an Everstone for returning to normal.
Sorry it took so long ;-;