Here is a list of the available Challenge Matches.

Undertaker

Christian

Rey

Cena

Jericho

• Week 4 - After the Peep Show, before talking to Tiffany, go to the top locker room on the map and talk to Regal. He will challenge you for Superstars.
• Week 5 - Find Kane and get challenged to an Inferno Match.
• Week 7 - Find CM Puink in the hallways and talk to him. He will fight you in an extreme rules match at Superstars.
• Week 9 - Find Jericho in the trainer's room. He will challenge you for Superstars.
• Week 11 - Find Legacy backstage. Fight them 2-on-1 at Superstars.
WrestleMania - Cash in against Edge, then check the Green Room to challenge Stone Cold

• Week 3 - Submission Match // Jericho
• Week 4 - 6 Man Tag // Los Conquistadors
• Week 6 - Singles Match // R Truth
• Week 9 - Singles Match // Bourne vs Orton (talk to Orton in top Locker Room at Elim Chamber to set this up)
• Week 10 - Cage // Hurricane (talk to him in the lower locker room to set this up before teaming with RVD)
• WrestleMania - Extreme Rules // Terry Funk (find him in the Green Room)
• Week 4 - Backstage Brawl // Confront Sheamus in the middle Locker Room
• Week 5 - Tag Match on SD // Fight Truth & Consequences (talk to MVP to set this up)
• Week 7 - Tag Match on SD // Truth & Consequences for the titles (unlocks civilian MVP)
• Week 8 - Backstage Brawl // Legacy (unlocks civilian Cena & entrance)
• Week 11 - Tag Team // with Santino vs Legacy
• WrestleMania - Singles Match // Vince in the Green Room
• Week 1 - Singles Match // The Miz
• Week 5 - Singles Match // Santino (talk to Santino at the Royal Rumble to set this up)
• Week 7 - Parking Lot // Cena
• Week 8 - Diva Match // Maryse vs Beth
• Week 11 - Singles Match // Santino vs Big Show (talk to Santino in the hall to setup your interference)
• WrestleMania - Singles Match // Find Steamboat in the Green Room