Read the sticky FAQ at the start of this forum and it will answer your questions. It is not nearly complete but it does answer your questions. Look elsewhere for a more complete FAQ.
You have to take the championship away from Reiko and then you will get the alter ego challange.
Also you need to defeat the original characters and another 5 or 6 to total 15 matches to get the championship.
And no the exibition matches do not count good or bad for any of this.