Roxas would never have known nor fused with Sora, so Sora would never have woken up and Roxas would never have realized his real identity.
DiZ needed Roxas to awaken Sora, so Riku awaited Roxas in Memory's Skyscraper. When Roxas fought and defeated Riku, Riku had to release his heart's darkness and assume Xehanort's Heartless' appearance to finally restrain and capture Roxas.
Towards the end of the game, you automatically fight Roxas in front of Memory Skyscraper.
Towards the end of the game, you automatically fight Roxas in front of Memory Skyscraper.
Riku defeated Roxas at Memory's Skyscraper in The World That Never Was.
Riku would most likely have tracked Roxas down, and finally released the darkness within him to stop Roxas. The only way that Roxas wouldn't have been stopped in the first place would be if Riku hadn't used the power of darkness at Memory's Skyscraper.
Sora's awakening would have been further delayed. Roxas would have eventually been stopped, even if Riku managed to let him slip by.
Yes. Memory's Skyscraper is found right before entering The Castle That Never Was. Memory's Skyscraper is most famous for the battle between Riku and Roxas during the secret Kingdom Hearts II teaser trailer; Deep Dive/Another Side Another Story.
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.
If you mean the first fight with Ansem, before his Final Form, keep dodging his Aerial Blade attacks, and when he swoops out of his block, strike him first. He is pretty easy to defeat. If he starts electrocuting you with a circle around you, run to the doors of Memory Skyscraper, and press triangle. If you time it perfectly, like the video where Roxas battles Riku, you will run up Memory Skyscraper and Ansem will jump off the top. Time you triangle pressing perfectly to slap him into Memory Skyscraper. Continue with these tips and you should be able to defeat him.
At the point in the game where you get to "the world that never was." When you get to the Skyscraper with Donald and goofy, sora will apear with roxas and they will fight, but YOU yourself do not get to fight roxas. Its all in story mode, so you can either watch it or skip it, but not play it.
Xion faded from existence, Roxas' memory was erased and he was placed in Twilight Town, and sadly everyone forgot about Xion.
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.