Ice Bear was found by Alvina when she went on a hike with her Gengar, Sneakers. Ice Bear's ability is Rattle, which means every time a move is used of a type that Ice Bear is scared of- in this case, fire- his speed stat gets boosted.
And since Alvina's ranch consists mostly of fire type Pokemon, Ice Bear does not have a good time and usually spends his days hidden away in the little icy grotto Alvina built for him.