Reconstructed Ko-Koro (ignore the fact the one hut covers the guideline and the massive creative liberties taken to the Bionicle location. I don't have any of the Bionicle games set in Mata Nui, and BionicleSector01 was not very helpful in terms of pictures. The site I would normally go to in order to ask about this is transferring to more efficient forum software and isn't available right now. Credit to the Lego group for the original location.)
A gigantic hollow enclave of ice, used as a village by an unknown tribe of small icy mechanoids. The arena is massive; the ordinary huts alone are 8-10 feet in diameter, and the arena overall is about 150 feet in diameter and about 120 feet in height. The triangular pillars are about 40 feet from their tips to the wall, are about 60 feet high, and extend on the wall for an arc of 40 feet. Pokemon that can climb using sharp hooks (or Rock Climb) can climb up the pillars, but they are otherwise too slippery to climb. The stairs leading to the pinnacle are 60 feet high and 110 feet long, reinforced with wood and metal chips; they were used for guards climbing to scout for dangerous monsters and have 60/4/5 defenses. The bridges are ten feet wide, about 15 feet from the wall, 4 feet high, and are reinforced with wood and metal chips; they have 45 HP and 3/4 defenses. The bridges and stairs alike are designed to provide more traction than usual. The lookout platform is 10 feet in diameter and coated in freeze-resistant, traction-granting resin. Falling from the pinnacle out of the arena is considered to be a Ring Out (treated as a KO.) Spiral staircases, about 8 feet in radius (not drawn to scale!) located within two of the spires allow players to climb to higher up the arena-if they can fit in it, of course. Fall damage from any significant height can be calculated as the ref desires.
A key is shown here:
http://www.majhost.com/gallery/ToaNeya/kits/CAP-9/OtherMons/CAP-ASB/arenakey.png
The cold environment and natural snow reserves make it easy for Hail to be whipped up. Snow Warning and Hail cost 2 less energy to execute. Ice-type attacks in general cost less to execute here thanks to both extreme cold and resident elemental energy, requiring 1 less energy than usual. On the contrary, the lack of natural gravel makes Sandstorms that much harder to summon, making Sandstorm and Sand Stream cost 2 extra energy. The trees can be used as plant matter for attacks. Stones are set beneath the deep snow; Rock Slide can be used from the bottom of the arena. Rain/Drizzle cost 1 extra energy to prevent the cold from freezing it over, and the Sun is so far in the sky that it only boosts Fire attacks by 1 point. (Solarbeam still doesn't require a charge-up in sunlight, although its base damage is reduced to 9 in sunlight.) Fire attacks require a little more power to summon; outside of Sunny Day conditions Fire attacks require 1 more energy than usual.
The huts might contain items; including rocks for attacking with (70%) and disks (50% chance, the probability is independent), which can be thrown as a Normal-typed ranged physical attack that deals 6 base damage and has 90% accuracy. The 20 foot radius giant hut, once used for their leader, contains a large stockpile of such disks.
Finally...yes, the snow can be used as a water source. It costs 2 more energy for types other than Fire (by heating up the ice) and Ice (by virtue of control), but it can be used as a water source nonetheless.