- Normal Kyurem: The default form. Normal Kyurem is a Pokémon that, along with Reshiram and Zekrom, were once a single dragon.
- Black Kyurem: A fusion form Kyurem assumes when merged together with Zekrom. It can learn the moves Freeze Shock and Fusion Bolt. It has the highest physical attack of all Ice Types so far.
- White Kyurem: Another fusion form Kyurem can assume when merged together with Reshiram. It can learn the moves Ice Burn and Fusion Flare. It has the highest Sp. Atk stat of all Ice Types so far.
Kyurem, along with Reshiram and Zekrom, are based on the concept of yin and yang in Taoism. However, Kyurem represents wuji, which is the absence of yin and yang, which would tie in with it's backstory with Reshiram and Zekrom.
Kyurem has received mixed reception initially, although some fans really enjoy the concept and lore it has.
When Pokémon Black 2 and White 2 were announced, and Kyurem was revealed to have two fusion forms, each form was met with generally positive reception for making Kyurem more viable in battle.
White Kyurem is the more favored fusion to use, since it has a usable movepool to take advantage of it's colossal Sp. Atk stat.
In regards to black Black Kyurem, though, some players are not happy with it's barren physical movepool to take advantage of it's monstrous physical attack. Despite that, it can make a fierce wallbreaker in OU, and can learn Roost for reliable recovery.
Regardless of whatever form Kyurem is using in battle, it has a fair share of drawbacks. As an Ice Type, it can be very vulnerable to many Fighting, Rock, and Steel Types, as well as the common setup hazard in competitive play; Stealth Rock.