Basically, make an album of songs that you wish your fave recorded

For me:

Xtina:

Haunted - Beyonce
Losing You - Solange
Honeymoon Avenue - Ariana Grande
Two Weeks - FKA Twigs
Right There - Ariana Grande
Hearts A Mess - Gotye
Together - The xx
XO - Beyonce
Dance For You - Beyonce
Body Party - Ciara
Almost Home - Mariah Carey

Britney:

Slow - Kylie Minogue
Into The Blue - Kylie Minogue
Go Go Dancer - Lana Del Rey
Take My Hand - Charli XCX
Give It 2 Me - Madonna

Songs I wish my fave recorded :

RIHANNA :

Sia:
Chandelier
Elastic Heart
Fire Meet Gasoline

Miley Cyrus:
We Can't Stop

Jays Wife
Drunk In Love
Partition

Jess Glynne:
Rather Be
Right Here

Ella Henderson
Ghost

She would've SLAYEDDDDDDDD them all

Rihanna

1. Sweet Dreams (Beyonce)
2. Burn (Ellie Goulding)
3. Chandelier (Sia)
4. Turn up the Music (Chris Brown)
5. Take You (Justin Bieber)
6. Woo Hoo (Christina Aguilera)
7. On the Floor (Jennifer Lopez)
8. Hold It Against Me (Rihanna)
9. Poker Face (Lady Gaga)
10. Dark Horse (Katy Perry)

Assuming the songs would be re-produced by them to fit their sound,

Rebecca & Fiona:
1. Bananarama - Cruel Summer
2. Jo Jo - Mind Games
3. Robyn - Hang With Me
4. Britney Spears - Soda Pop
5. Ace of Base - Happy Nation
6. 'Til Tuesday - Voices Carry
7. Pet Shop Boys - Heart
8. ABBA - Take A Chance On Me (They've covered it live but I need that studio rip)