Sonic Battle

Sonic Battle is a fighting game for the Game Boy Advance. The game play consists of 2D sprites fighting in 3 dimensional environments similar to the Double Dragon games. The special move configuration is very similar to Super Smash Bros. in that you can pick it up and play, and that there are no complicated combos you need to memorize to perform special moves.

Story
About 4000 years ago, a sentient weapon was created by an ancient civilization. After being lost for millennia, the weapon, called a Gizoid, was unearthed and researched by Prof. Gerald Robotnik. It remained dormant for another half century before being discovered by, of all people, resident would-be ruler of the world and Gerald's grandson, Dr. Eggman. Frustrated at his inability to get the dormant Gizoid to work properly, Eggman dumped the contraption at Emerald Beach... where it was discovered once again, this time by planet's resident hero, Sonic the Hedgehog.

The Gizoid, which Sonic dubs Emerl, gets wrapped up in the affairs of Sonic's friends, allies and rivals. Through his encounters with Sonic, Tails, Knuckles, Amy, Cream, Gamma, Rouge, and Shadow, Emerl grows and evolves from a soulless robot into a fun-loving mech with personality traits from all of the above. But while the gang is having fun raising their new mechanical toy, there are those who recognize Emerl's true power. Now that the Gizoid is working again, Eggman's got his eye on it, Rouge wants to turn it into a master thief, and Shadow senses that, despite their efforts to humanize him, Emerl is still designed and programmed to be a weapon of mass destruction.

The story comes to a close when Dr. Eggman challenges Emerl to a battle aboard his new Death Egg. While Emerl is able to defeat the mad doctor, Eggman takes advantage of Emerl's core programming - to obey whoever is strongest - by using the Death Egg's Final Egg Blaster to take out several stars. However, the programming conflict between Emerl's new personality and weapon design cause Emerl to lose control. He knocks out Eggman and turns the Final Egg Blaster on Earth. Sonic attempts to use the Master Emerald to neutralize Emerl's Chaos Emerald powers, but when that fails, he's forced to defeat him in combat. With a final goodbye, Emerl is destroyed, but Sonic believes that they'll see him again someday.

Unlockable

 * E-102 Gamma (Chaos Gamma, no episode)
 * Chaos (No episode)
 * E-121 Phi (Only in multiplayer mode when two or more people choose the same character)

Arenas/Unlockable
All arenas except for Death Egg can be used in Multiplayer.
 * Emerald Beach (Sonic, Tails and Emerl's story)
 * Tails' Lab (Tails, enter to virtual training in Emerl's story)
 * Chao Ruins (Knuckles)
 * Battle Highway (Shadow)
 * Club Rouge (Rouge)
 * Amy's Room (Amy)
 * Library (Cream)
 * Metal Depot (Chaos Gamma)
 * Holy Summit (Chaos)
 * Death Egg (has to be unlocked by completing story mode)
 * Colosseum (used during virtual training, only available during Emerl's story
 * Green Hill (has to be unlocked by completing story mode)

Trivia

 * Oddly, the seven Chaos Emeralds are all green in this game, and the Master Emerald does not have its own separate sprite, while the shattered emerald has its own sprite for the shards.
 * Strangely, when Sonic gets the Master Emerald, he states "A Master Emerald" but this might be a typo.
 * The story is later continued in Sonic Advance 3 (in which a new robot, Gemerl, is built from Emerl's data), and heavily referenced in Sonic Chronicles: The Dark Brotherhood.
 * Though the seven Chaos Emeralds are featured, Sonic doesn't use them at any time to go Super Sonic.
 * For some reason, when you have six emeralds, and Shadow has one there are still shards of a full emerald.
 * When Chaos Gamma appears before Sonic, Tails, and Emerl, Sonic and Tails quickly recognize Gamma, who they haven't seen since Sonic Adventure. Knuckles and Amy also remember Gamma. Rouge notes that he looks similar to Omega.
 * When entering Central City, a blue sign that reads "Sonic Team" is easily seen. Emerl can also enter it in his story but requires various passwords which unlock battle cards.
 * In the Japanese version of this game during Rouge's story, in the cutscene when she finds Eggman hacked into the Central Computer, Rouge calls him a "dirty bastard".
 * Knuckles' walking animation is similar to his running animation in Sonic & Knuckles.
 * The first Sonic game with 2D artwork not done by Yuji Uekawa