It first appeared along with its trainer, Greta, when all the Frontier Brains were introduced to the audience. Umbreon later used Quick Attack on Emerald to silence him because he spoke too much.
Umbreon was with Greta, who visited Noland in the hospital. Umbreon was standing next to Greta when the Frontier Brains, except Pyramid King Brandon, confronted Emerald to know where he got his Sceptile. Umbreon later attacked the group of Smeargle when they arrived in the Artisan Cave. Guile Hideout appeared and the Frontier Brains, except Salon Maiden Anabel, immediately attacked him as Greta revealed that he was the one who attacked Factory Head Noland after seeing the rental Poké Balls. Umbreon used Double Team and attacked the group of Pokémon that Guile Hideout released.
Greta sent out her Umbreon in her battle against Emerald and his Dusclops. Umbreon used Faint Attack on Dusclops and then dodged Dusclops' Will-O-Wisp. It immediately used Confuse Ray after the attack and confused Dusclops. Dusclops was then knocked out and Umbreon won the battle. Emerald sent out his Sudowoodo and it was then known that Umbreon had the burn status. It tried to eat its Leftovers but was easily knocked out with Sudowoodo's Low Kick. Umbreon protected the guests, who wanted to see the battle between Emerald and Dome Ace Tucker, by attacking the rental Pokémon Guile Hideout released. Umbreon appeared next to its trainer when the Frontier Brains visited Emerald after the whole crisis.
|Quick Attack||Interesting Interactions Involving Illumise|
|Double Team (move)||Skirting Around Surskit I|
|Faint Attack||Sneaky Like Shedinja I|
|Confuse Ray||Sneaky Like Shedinja I|
|+ indicates this Pokémon used this move recently.*|
- indicates this Pokémon normally can't use this move.
- ^ EM002: Swanky Showdown with Swalot
- ^ EM003: Interesting Interactions Involving Illumise
- ^ EM010: Chipping Away at Regirock
- ^ EM011: You Need to Chill Out, Regice
- ^ EM012: A Sketchy Smattering of Smeargle
- ^ EM013: Skirting Around Surskit I
- ^ EM015: Sneaky Like Shedinja I
- ^ EM024: Lemme at 'Em, Lapras!
- ^ EM035: Epilogue