Pokémon Colosseum (Japanese: ポケモンコロシアムPokémon Colosseum) was released on the Nintendo GameCube on November 21, 2003 in Japan, March 22, 2004 in North America, and May 14, 2004 in Europe. The game followed the basic stadium style battling found in the Pokémon Stadium games, but extra gameplay was included in the form of an RPG story mode comparable to the core series, which allowed Trainers to catch Generation II and Generation III Pokémon in the desolate region of Orre.
In this game, the player characterWes was formerly a member of an organization called Team Snagem, which had obtained a machine that allowed the user to "snag" another Trainer's Pokémon as though it were wild. Another team, Cipher, was responsible for corrupting the hearts of Pokémon and giving them to Trainers. With the help of a young girl named Rui, Wes was able to find the Pokémon whose hearts were sealed and surrounded by a purple aura and use the Snag Machine to rescue Shadow Pokémon and restore them to normal.
The game starts with an opening scene depicting the player stealing equipment from the strongly guarded headquarters of Team Snagem, and then proceeding to flee with an Espeon and Umbreon as the base explodes. After riding on a strange one-wheeled motorcycle for a while, the player stops at the dilapidated gas station of Outskirt Stand. The player battles Rider Willie, who tells the player about Phenac City after he is defeated.
Upon reaching the new location, a pair of shady people are just leaving the city with a noisy, wriggling sack in tow. Once they see that they've been caught, one of the goons, Folly, starts a battle with the player. After defeat, both people get away, leaving the sack unattended. A girl emerges from the bag after some trouble undoing the knot, and claim to have seen the kidnappers use some kind of strange looking Pokémon. The girl becomes the player's partner and both go to find the Mayor to clear things up. A strange man bumps into the player as he leaves the Mayor's office, predicting that he will see the player again sometime in the future. The player and partner then enter the house as the girl proceeds to alert the Mayor of weird Pokémon that have a dark aura and attack humans. The Mayor assures the team that he will look into this case, and suggests going to the city's Stadium. At the doorway of the Stadium, some Snagem members recognize the player as the traitor who blew up their base. A battle with one of them ensues, and upon defeat, the girl tells the player that she doesn't care about the past, but she does encourage buying some Poké Balls for future use. After this scene, the girl, Rui, becomes the player's permanent partner, and will follow the player throughout the length of the game.
Then, after purchasing some Poké Balls at Outskirt Stand, the player returns to Phenac City, only to find it taken over by some thugs. The player tries to rescue the Mayor, but finding the decked-out Miror B. and his mischievous friends in his wake. The player's partner identifies the first Shadow Pokémon available for capture after entering a battle with Miror B.'s underlings, Folly and Trudly. After beating both in a battle, and/or capturing the Shadow Pokémon, the player tries to leave the city for Pyrite Town, but is waylaid by brightly clad goons at each exit. Each has a Shadow Pokémon, but defeat of one will cue the others to leave.
From this point, the player and partner will journey all across the Orre region, battling Trainers, snagging Shadow Pokémon, and uncovering the disastrous plan of the secret organization, Cipher. This shady group and its ambitious admins are the creators of Shadow Pokémon, closing their hearts to strengthen their stats. The player eventually learns how to reverse the effects of this process, and must capture all of Cipher's Shadow Pokémon to thwart the evil mastermind behind it all. After defeating Miror B in Pyrite Cave, Dakim in Mt. Battle, Venus in The Under and Ein in the Shadow Pokémon Laboratory, the player goes to Realgam Tower; after defeating the Admins again, Gonzap comes out and reveals that Cipher gave Team Snagem the Snag Machines; and that Snagem gave the Pokémon to Cipher, who created Shadow Pokémon; meaning that this was all one master plan hatched by Cipher. After defeating Snagem, Nascour—the boss of Cipher—is defeated by the player. Afterwards, it is revealed that Phenac City's mayor Es Cade is actually Evice, the true boss of Cipher. After he is defeated, he tries to escape; however, fortunately, a Ho-Oh uses Sacred Fire to stop him, saving the day.
Even with the true leader of Cipher under arrest, there is still a post-ending to be completed. Secc, from the Kids Grid, emails the player information about some interesting characters who end up telling the player about some points of interest. Eventually, the Snagem Hideout becomes available for exploration, the Shadow Pokémon Laboratory gets some Cipher refugees to battle, and a hidden Stadium in the Under is brought to the player's attention. Lastly, after all the Shadow Pokémon are snagged, the player will be notified of a Trainer that is attacking people with another Shadow Pokémon, who supposedly looks just like the player. After the copy's defeat, there are still Colosseum battles to be won and a Ho-Oh to be obtained in Battle Mode.
Story Mode: Gotta Save 'em All! In the new Orre region, a sinister organization is capturing Pokémon and misusing them. It's up to you to restore balance. Seek out all the Shadow Pokémon, snag them, and restore their spirit.
Unleash your Pokémon from Story Mode or send in your team from Pokémon Ruby or Pokémon Sapphire! Let them show off their true power in Single, Double, and Multi Battles! Battle Mode: Worlds Collide!
This section is incomplete. Please feel free to edit this section to add missing information and complete it.
Once the Heart Gauge reaches the point where it says "The Pokémon's heart is about to open! Undo the final lock!", Trainers would go to the Agate Village shrine and use its power to restore the Pokémon's heart and remove the move known as Shadow Rush. Once the Pokémon has been purified, it will gain all experience and friendship it earned during the time it was a Shadow Pokémon, and acquire a special Ribbon exclusive to purified Pokémon. No effort values are earned until the Pokémon has been purified.
After players have beaten the game, Pokémon can be traded to all Generation III games provided that their hearts are open (and certain objectives have been completed in FireRed and LeafGreen, if they are being traded to). Note that trading Pokémon to Ruby and Sapphire will not unlock the National Pokédex.
In Phenac City, the player is given a choice between Bayleef, Quilava, or Croconaw. The other two will be available later in the game, after the credits roll. The Pokémon whose type is weak to the chosen Pokémon's type will be at the Snagem Hideout and the Pokémon whose type is strong against the chosen Pokémon's type will be at the Shadow Pokémon Laboratory.
Plusle is given to Wes by Duking after Wes saves it from Cipher. He asks Wes to protect it from harm and to make it stronger.
Ho-Oh is obtainable in Pokémon Colosseum when all of the 48 Shadow Pokémon have been snagged and purified. Players would then have to use a team of Pokémon from the RPG to clear Mt. Battle in Battle Mode from zones one to 100.
Colosseum Battle allows players to participate in various challenges that can earn the player Poké Coupons. Along with a different version of the Mt. Battle 100-Trainer Challenge, Colosseum Battle also consists of several Colosseum venues to which Trainers can send Pokémon from the RPG or the Game Boy Advance games to battle.
While competing in the Mt. Battle 100 Trainer challenge in either the RPG or the Colosseum section of the game, players can receive Poké Coupons which can be used to buy items. Additionally, players have the option of storing Poké Coupons on a Pokémon Ruby or Sapphire game pak for later use. Below is a list of what players can receive after collecting a set amount of Poké Coupons.
Pokémon Colosseum is compatible with all five of the core series Pokémon games on the Game Boy Advance. Items and Pokémon can be traded between them in the same manner that they can be traded between each other, however, the player must have defeated Evice in the main story mode in order to unlock it, have a GameCube-Game Boy Advance cable, and a Game Boy Advance.
If a Pokémon is traded from Pokémon XD to a GBA game and then to this game, the caught location will most likely be displayed as Mt. Battle, regardless of where it was actually caught in Orre, even if it was caught in an area accessible in the game, because both games use exactly the same internal index list for locations. Doing the reverse also produces a status screen oddity.
The Pokémon Storage System only has 3 boxes, thus allowing a maximum of 90 Pokémon to be stored. As there are no wild Pokémon to be caught and trading yields no additional Pokémon, the player normally can never get more than the 48 ordinary Shadow Pokémon, the three Japanese e-Reader-exclusive Shadow Pokémon, Espeon and Umbreon, and two gift Pokémon. However, when a Nincada evolves, the game still creates the additional Shedinja, thus allowing the player to keep the purified Pokémon in the game plus more from other games. If the player attempts to catch a Shadow Pokémon with full PC boxes and party, the message "The box is full. You can't Snag any more Pokémon." will be displayed.
None of the Pokémon obtainable in the game are from Generation I.
A trailer for Pokémon Colosseum was included on the bonus disc that came with preorders for Mario Kart: Double Dash!!. The trailer shows an early, more simplistic logo for the game, followed by various story and battle footage with Japanese text.