I've seen a beartic deck before. Its rather funny imo.
Heres a quick list i just threw together. It needs tweaking of course. But its got the general idea.
Pokemon: 19
4-4 beartic PLS
4-4 Umbreon PLF
1 Leafeon PLF
1 Keldeo Ex
1 Articuno Ex
Supporter: 13
4 Juniper/Sycamore
3 N
3 Shauna
1 Pokemon Fan Club
2 Lysandre
Trainer: 14
2 Level Ball
3 Plasma Ball
1 Super Rod
1 Pal Pad
2 Float Stone
2 Startling Megaphone
3 Giant Cape
Stadium: 2
2 Frozen City
Energy: 12
4 Rainbow Energy
8 Water
Basic plan is to get frozen city out, then attach rainbow energy to damage cubchoo 3 damage counters per rainbow energy, then evolve to beartic. Umbreon provides tons of hp with giant capes. Keldeo/Float stone for switching. 1 Leafeon just because Leafeon is good. Then start swinging for massive damage.
With this set up, beartic can get up to 230 hp. After taking 10 damage counters, beartic starts hitting for 200 damage for only 2 energy. With 130 hp remaining. Articuno Ex also gets tons of Hp. Hitting up to 270 hp.