Chao Karate is an event in which Chao can compete. This event can be accessed by going to the Neutral Garden in Sonic Adventure 2: Battle. By going through a tunnel in the Garden, the player can access the Chao Stadium. The game itself presents two options for the player: Inter-league Game and the Tournament. The Tournament option is the main game, in which the player's Chao can fight a rival computer-controlled Chao. The Interleague Game option allows a Chao from the Memory Card in Slot A to battle a Chao from Slot B.
The game itself has several levels of difficulty, ranging from Beginner, Standard, Expert and Super. Super mode is unlocked once the player completes Expert mode. The player's Chao's stats can contribute different traits that would enable it to win the battle. Chao Karate provides the player's Chao with a variety of opponents in the different tournaments and the battles are animated in a comical style.
In Chao Karate, the player will have two options of for gameplay: the Inter-league Game or the Tournament. The Tournament is the main Chao Karate game, in which the player's Chao faces off against a computer-controlled Chao. The Inter-league Game, however, allows a Chao from the Memory Card in Slot A to battle a Chao from Memory Card Slot B.
There are four levels of game play in the Tournament mode: Beginner, Standard, Expert and Super. When the player completes a level, they advance to the next, which increases the difficulty. Each level also has five opponents, which the player's Chao must defeat in order to advance to the next battle.
The player's Chao's stats contribute different traits that help it win a battle. For example, Stamina is Health, Swim is Defense, Fly is Stealth, Running is Speed, and Power is Power. There are two meters at the bottom of the screen that show the Chao's Zeal and that of its opponent. Zeal is the Chao's will and energy to compete. When the Chao runs out of Zeal, it will start playing around, leaving it vulnerable to attacks from its opponent. The player can try to prevent this prior to battle by feeding their Chao lots of fruit to raise its Stamina, which in turn raises its Zeal. On the occasion when it does run out of Zeal during battle, the player can cheer on his or her Chao—by rapidly pressing the A button— to get it back in the game. Successfully attacking an opponent will raise a Chao's Zeal slightly, while getting attacked or its opponent dodging an attack will significantly lower its Zeal.
In Chao Karate, the Chao attack each other by comically punching and kicking each other. Chao with high power can learn to wind up for a stronger punch and spin around for a more powerful kick. If a Chao runs out of Stamina and starts crying, or falls off the platform, that Chao loses the battle. Sometimes, a Chao will dodge its opponent's attack by jumping out of the way just before its opponent strikes.
Opponent #4: Eggie, a baby neutral Chao with a regular egg shell for a hat, or Dinner, a baby neutral Chao with a pan for a hat.
Opponent #5: Happy, a baby neutral Chao with all bunny parts and an apple for a hat.
Opponent #1: Lucky, a dark swim Chao with a paper bag for a hat.
Opponent #2: Smokey, a regular neutral adult Chao with a pumpkin for a hat or Melody, a hero Chao with strange bunny parts and wears a flower pot for a hat.
Opponent #3: Stormy, a hero power Chao with a yellow and red striped wool hat.
Opponent #4: Spooky, a neutral run Chao with a blue-striped wool hat.
Opponent #5: Stinky, a dark fly Chao with a gray-striped wool hat.
Opponent #1: Chappy, a dark normal Chao with a cardboard box hat, or Magic, a hero run Chao.
Opponent #2: Ninja, a dark fly Chao, or Skull, a neutral fly Chao with a skull hat.
Opponent #3: Tin, a hero swim Chao with a tin bucket hat, or Woody, a neutral swim Chao with a tree stump for a hat.
Opponent #4: Rainbow, a dark power Chao.
Opponent #5: Wacky, a neutral run Chao who seems to have a short-temper personality.
Opponent #1: Crunch, a neutral run Chao with a watermelon hat.
Opponent #2: Wacky, the short-tempered neutral run Chao who has come back for revenge with dragon horns.
Opponent #3: Crystal, a gold Angel Chaos Chao.
Opponent #4: Angel, an aquamarine jewel Devil Chaos Chao.
Opponent #5: Flash, an onyx jewel Light Chaos Chao.
Wacky is the only Chao to appear in two difficulties.
Sometimes, when fighting Stormy, Spooky or Crystal there is a glitch in which he kicks the player's Chao and, if possible, might end the match instantly.
Both Rainbow and Wacky don't have crying animations when defeated. Wacky stomps on the ground while Rainbow appears to be "crying."
It is impossible to have the same beginning animations as the opponents. For example; Happy's beginning animation is singing and facing the player.
For some reason, Crystal is the name of the Super Rank Angel Chaos Chao in the third round, and Angel is the name of the Super Rank Devil Chaos Chao in the fourth round.
Unlike in Chao Race, where an exit would simply exit the race, hitting exit in the pause menu while fighting in Chao Karate exits the Chao Garden altogether, forcing you to have to return through Stage Select or by getting a Chao Key and finishing a level.
The Zeal-Bar drops slower, the more Intelligence a Chao has. Luck is how fast your Chao can restore the Zeal-Bar. And Stamina is how much Health a Chao loses, when hit.