Cerberus is a mythical three-headed demon dog that first appeared in Disney's Hercules, as guard dog to the Underworld. Hades used his pet in both Kingdom Hearts and Kingdom Hearts II.
Like the Behemoth, in Kingdom Hearts, Cerberus is at his strongest stat-wise during the Hades Cup; stats are not shown. Also during the Hades Cup, you will gain 1000 EXP for defeating him the first time; every time after that, you will only gain 100 EXP.
Journal Entries
Kingdom Hearts
Guardian of the entrance of the Underworld and Hades's loyal servant. Herc defeated him once, but Hades has brought him back to fight Sora and his friends.
It first stood watch for Hades in "Hercules" (1997).
Kingdom Hearts II
Hercules (1997)
Guardian of the entrance to the Underworld and Hades' loyal "pet."
Hercules, Sora, Donald, and Goofy teamed up to defeat it last time, but Hades brought him back -- and he's as dangerous as ever.
Appearances
Story
Kingdom Hearts
In Kingdom Hearts, Cerberus acts as a back-up plan for Hades, if Cloud, whom Hades promised to help find Sephiroth for him, fails his task of eliminating Hercules and Sora.
When Sora and Cloud's battle comes to an end (regardless of who wins), Hades sees that Cloud is no longer of any use to him, and sends Cerberus in. Cerberus manages to pin the Buster Sword to the ground when his back is turned, and is about to attack the others, but is held off by Hercules, allowing Phil, Sora, Donald and Goofy to escape.
Cerberus has Hercules, who is carrying Cloud, trapped, but Sora comes to help, returning the favor and allowing Hercules to escape. Sora manages to defeat Cerberus, and his efforts reward him the status of "Junior Heroes". However, as Sora leaves, Hercules mentions to Phil that he had already worn Cerberus down by the time Sora intervened.
Cerberus can be fought again in full power at the Hades Cup, having four health bars instead of two (thus proving the fact that Hercules had worn it down). However, Since the first time you may not have got Cure, he might seem easier the second time you fight him.
Kingdom Hearts II
In Kingdom Hearts II, as Sora, Donald, Goofy, and Auron are escaping from the Underworld, Hades sends Cerberus to stop them. Donald and Goofy escape as Auron fights off the creature. Sora returns to aid him, but ends up separated from Donald and Goofy, leaving him and Auron to fight the monster by themselves. The two then manage to get away, and Cerberus is trapped behind the doors as they close, but not before Sora, Donald, and Goofy taunt him by making faces. Cerberus has its own cup in the underworld, being the final opponent of the Cerberus Cup in a timed fight.
Strategies
Kingdom Hearts
It is important to be able to climb on top of Cerberus's back, in order to avoid his Dark Breath attack and his Fireballs. Alternatively, you may use Dodge Roll to avoid Cerberus' Dark Breath attack, as well as the Guard ability to deflect his fireballs. (Note: going under Cerberus' back when he uses Dark Breath will not work.) Use his back and the stairs as places to heal yourself, which is important to do often. Be sure to have a load of items like Ethers and Potions. Do not rely on Donald for healing, as he dies quickly, especially in the first battle. Be sure to lock on and attack the heads on the side, not the middle head. Use Dodge Roll and Glide (or alternatively, Superglide) often to get away from his Bite. Keep attacking the heads with your Keyblade and a combination of Fire and Thunder magic to finish him off.
Kingdom Hearts II
Cerberus is back with a whole new range of attacks. In this fight, you battle alone with Auron, so use his strong Limit attack to deal loads of damage. Unlike the first game, climbing on Cerberus's back is unwise, due to his spinning attack that throws you off and deals damage in the process. Instead, use the edges of the large battle field to heal while Cerberus is far away. Try to stay locked on to him in order to track his whereabouts, as Cerberus jumps across the battlefield quite often. Keep your target on his outer heads. Look for the reaction commands that occasionally appear when Cerberus is stunned, to deal a lot of damage. Fire and Thunder magic help to attack Cerberus from far away. In this fight, if you die as Sora, you will have the choice to turn into Mickey Mouse. Try to get his hp down while playing as Mickey. Once you do, revive Sora and end the battle.
You fight him alone as the top seed of the Cerberus Cup and the Cerberus Paradox Cup (i.e. without any party members), so be prudent about his attacks. Using Final Form is recommended - use it to the best of your ability as Sora can use Drives alone.