XBOX 360/PS3/PC/XBOX ONE: BiPolar Bear can be obtained at the end of Snow World. To obtain him, the Horn must be used. Blow the Horn in front of the cave leading to the Ice Castle level, next to the Horn sign, and BiPolar Bear will emerge, allowing the player to obtain him.
BiPolar Bear will maul any player, character, or enemy of any sort with less than 11 HP. The fact that he mauls even his owner seems like a bad thing at first, but over time players develop skill and work around it, because most of the time the chances of your health bar being at or below 11 HP are astronomical; in simpler terms, BiPolar Bear is only bad for you if you're an embarrassing lack of skill. A nice bonus to this is that he'll prevent overkill because you'll know exactly when an enemy is dead. Many experienced players tend to overkill with their juggles because they'd rather play it safe than sorry, and BiPolar Bear trims that process down exponentially to play efficiently all around. BiPolar Bear is as efficient for farming as he is in regular gameplay because of this.
BiPolar Bear will maul any boss with less than 11% of their HP left; notice that's a percentage, not total. BiPolar Bear is the single best pet to bring to any boss fight because of this. You get XP every time he hits the boss, so even though you're not attacking the boss you'll still reap the benefits. BiPolar Bear does 32-96 damage per hit; hitting 3-4 times a second. Upon actually hitting the boss when this happens, the boss will die instantly.
"Weapon Effect Usage"
Like Hawkster, BiPolar Bear can Freeze, Shock, Burn, Poison, or Critical Strike. Given, if the appropriate weapon has the listed effect.
As BiPolar Bear attacks any injured character, keep in note that it will also attack yourself if you're low on health while competing for a princess or while fighting in arenas in co-op modes.
BiPolar Bear combined with the Ribeye and Saracen, Bear, or Orange Knight, are considered some of the deadliest and most efficient character/pet/weapon combos in PvP; although Bitey Bat may be better.
BiPolar Bear will automatically maul the Painter's paintings when the Painter begins to move all over his room when his health bar's significantly depleted.
As soon as BiPolar Bear gets really close to enemies that are being juggled, he will begin "fidgeting" around the airborne enemy. This is the best indicator of the player over-killing the enemy within a juggle. However, this may not always be an accurate estimate of overkill if multiple enemies are involved within the juggle; usually, with the juggle being either a lightweight or mediumweight juggle depending on the level and enemy types.