Gaiien Region: Eelvolutions: Vitreel, Silteel, Marqueel, and Erebeel

Real eels don't curl up like a snake, but these pokemon are of course not eels, but energy lifeforms imitating animals.

Vitreel → (Smoky Gem) Silteel
Vitreel → (Thunder Stone) Marqueel
Vitreel → (Dusk Stone) Erebeel

#026 - Vitreel (vitreous + eel)
Glass Pokémon
Water-type
They are nearly transparent so that they can better absorb environmental energy. Thousands of them disperse in the spring, and they take evolved forms based on compatible habitats.
Learnset: Bubble, Water Gun, Splash

#027 - Silteel (silt + eel)
River Pokémon
Water/Ground-type
A slow, indolent pokémon, they often spend time buried in river beds or drifting with the current. They often prank other pokémon who come to the riverside to drink.
Base Stats: 95/65/95/65/95/65 (480)
Ability: Water Absorb/Damp (prevents explosive moves and self-fainting)
Learnset: Wrap, Mud-Slap, Mud Shot, Muddy Water, Mud Bomb, Mud Sport, Earth Power, Quicksand, Whirlpool, Undertow, Aqua Jet, Bubblebeam, Bubble Blast, Rain Dance, Water Sport, Sand Shell, Shore Up

#028 - Marqueel (marquee + eel)
Flashing Pokémon
Water/Electric-type
They are playful, a common sight in coral reefs. They gather energy from thunderstorms and the change in the tide.
Base Stats: 65/65/65/95/95/95 (480)
Ability: Volt Absorb/Illuminate (nullifies moves that obscure battlefield or cause darkness)
Learnset: Wrap, Thundershock, Shock Wave, Charge, Charge Beam, Thunder Wave, Thunderbolt, Thunder, Bubblebeam, Bubble Blast, Rain Dance, Water Pulse, Water Sport

#029 - Erebeel (Erebus + eel)
Abyss Pokémon
Water/Light-type
On the abyssal plain, there is little energy, but it can steal from other pokémon and take prey. It lures them in with its lights.
Base Stats: 70/95/70/65/70/110 (480)
Ability: Light Absorb/Nightmare Moon (speed increases under night/darkness effect)
Learnset: Wrap, Spotlight, Flash, Shining Eye, Searchlight, Beacon, Rebuke, Haloed Tackle, Shining Lance, Aqua Jet, Aqua Tail, Waterfall, Whirlpool, Undertow, Night Slash