The Ice Fighters are a trio of Ice-type Pokémon who were hired by Nuzleaf, and Diggersby to kill Mark and his friends. But they were all brought down by Shadow.
Avalugg: the sturdy basher of the Ice Fighters and the turtle like Pokémon with his great strength to break any wall. He was killed by Shadow during his fight with Froakie.
Beartic: the swift blizzard of the Ice Fighters and a polar bear like Pokémon with his great speed to hit his targets. He was killed by Shadow during his fight with Treecko.
Weavile: the leader, the cold slicer, and the strongest member of the Ice Fighters his sharp claws can slice trough anything. He was killed by Shadow during his fight with Mark.
Froakie vs. Avalugg
Treecko vs. Beartic
Mark vs. Weavile