This Vanillite is an Ice-type Pokémon owned by Trip.
Trip used Vanillite to try and catch a wild Palpitoad, but failed, since Ash interfered. Later on, Trip sent Vanillite to battle Ash's Tepig, since Trip wanted to "beat Ash at his own game" by using a Pokémon with type disadvantage. Vanillite used Ice Beam to slow down Tepig, who used Flame Charge. Tepig got hit by Vanillite's Icicle Crash and retaliated with Ember, hitting Vanillite, who attacked with Ice Shard. To finish, Vanillite and Tepig exchanged blows by using Blizzard and Flame Charge. Both Pokémon were knocked out, causing Ash and Trip's battle to end in a draw.
Vanillite was also seen in a flashback, when its Blizzard tied with Tepig's Flame Charge.