Sorry, but no. I have beaten Sora and Riku's story, and it is only one player.
No, she is one of the puppets that Vexen created. For example, in Kingdom Hearts Chain Of Memories and Rechain of memories (the version for PlayStation2) he created a puppet Riku to lure Sora in so Namine could erase his memory so Vexen, Axel, Marluxia, and Larxene could have Kingdom Hearts for themselves. Yeah, they were going to use him. :0
sora is trying to find his lost memory's
If my memory is correct I believe you go back to Jaq.
In order to use any kingdom hearts codes, you need a Gameshark. You can buy one at Wal-Mart where memory cards are sold.
You only get to fight Ansem and his Guardian in Kingdom Hearts and Kingdom Hearts Chain of Memories, while playing as Riku. However, you see the Guardian again when Riku unleashes his darkness to beat Roxas in Memory's Skyscraper.
Kingdom Hearts Chain of Memories is an extra game that is about the story between Kingdom Hearts and Kingdom Hearts II. It's a game based on how Sora must retrieve his scattered memories. I hope this helped. The game is set in an old castle, which makes u lose ur memory the more further u go inside. No more info! play for urself now
Towards the end of the game, you automatically fight Roxas in front of Memory Skyscraper.
The keyblades stand for each of the worlds Sora visit or a memory of Sora's.
SPOILER Because Namine has to put his memory back together.
No. After Xion tells Roxas to set the hearts free, Roxas goes to The World That Never Was, and is confronted by Riku, who defeats him by giving in to the darkness in his heart. Riku then gives Roxas to DiZ, so that DiZ may rewrite Roxas's memory. (this is also the beginning of Kingdom Hearts II)
Riku is seen with the Oblivion when Roxas fights him at Memory's Skyscraper in Kingdom Hearts 358/2 Days. He also wields the Oblivion when Sora fights him in Hollow Bastion in Kingdom Hearts 1.
Towards the end of the game, you automatically fight Roxas in front of Memory Skyscraper.