What songs to sing? America's Got Talent Competition?

My sister wants to try out for America's Got Talent. She just turned 12 last week. She has an amazing voice and sounds like Christina Aguilera did at 12. She has a very diverse voice with a big vocal range. I want her to sing songs from different genres. She as down the following songs: There will come a day - Faith Hill, Blessed - Rachel Lampa, Bubbly- Colby Caillat, Wasted - Carrie Underwood, I'll Stand By You - Pretenders, Home - Chris Daughtry, Redeemer - Nicole C Mullen, Jesus, Take the Wheel - Carrie Underwood. Does anyone have any suggestions? She needs some rock songs? Indie? Ella Fitzgerald songs? Beatles? Mariah Carrey?