Duets

Ballad-oriented:

A Great Big World & Christina Aguilera - Say Something
Anouk & Kane - My Best Wasn't Good Enough
Ariana Grande & Nathan Sykes - Almost Is Never Enough
Babyface & Stevie Wonder - How Come, How Long
Brandy & Wanya Morris - Brokenhearted
Brandy & Ray J - Another Day In Paradise (cover)
Brian McFadden & Delta Goodrem - Almost Here
Britney Spears & Don Phillip - I Will Still Love You
Christina Aguilera & Ricky Martin - Nobody Wants To Be Lonely
Christina Aguilera & Luis Fonsi - Si No Te Hubiera Conocido
Daniel Merriweather & Adele - Water And A Flame
Elisa & Jack Savoretti - Waste Your Time On Me
Enrique Iglesias & Whitney Houston - Could I Have This Kiss Forever (original version, 4:22)
Gareth Gates & Will Young - The Long And Winding Road (cover)
James Morrison & Nelly Furtado - Broken Strings
Jessica Simpson & Nick Lachey - Where You Are
Kelly Clarkson & Vince Gill - Don't Rush
Kris Allen & Lenachka - Prove It To You
Kylie Minogue & Nick Cave - Where The Wild Roses Grow
Luther Vandross & Mariah Carey - Endless Love (cover)
Maria Mena & Mads Langer - Habits
Niall Horan & Maren Morris - Seeing Blind
OneRepublic & Sara Bareilles - Come Home
Rascal Flatts & Lauren Alaina - Are You Happy Now
Rascal Flatts & Natasha Bedingfield - Easy
Richard Marx & Toni Braxton - Suddenly
Ricky Martin & Meja - Private Emotion
Stevie Wonder & Aisha Morris - How Will I Know
Stevie Wonder & Dionne Warwick - Weakness
Tamia & Eric Benet - Spend My Life With You
Taylor Swift & Gary Lightbody - The Last Time (Taylor's Version)
Tori Kelly & Ed Sheeran - I Was Made For Loving You
Troye Sivan & Alex Hope - Blue
Two Spot Gobi & Jason Mraz - Tomorrow
U2 & Mary J. Blige - One
Walters & Kazha - The War Is Not Over
Westlife & Delta Goodrem - All Out Of Love (cover)
Whitney Houston & Jermaine Jackson - If You Say My Eyes Are Beautiful
Whitney Houston & Mariah Carey - When You Believe
Youssou N'Dour & Neneh Cherry - 7 Seconds

Non-ballads slow ones:

Faithless & Dido - One Step Too Far
NEEDTOBREATHE & Gavin DeGraw - Brother
The Weeknd & Ed Sheeran - Dark Times
The xx - Basic Space / Crystalised / Infinity

Heavier slow ones:

Bowling For Soup & Gabriel Mann - Turbulence
Chad Kroeger & Josey Scott - Hero
Seether & Amy Lee - Broken
Sita & Kyo - Le Chemin

Uptempo (pop-oriented):

Brandy & Monica - The Boy Is Mine
Brian McFadden & Delta Goodrem - Mistakes
Brian McFadden & Christian Lo Russo - Not Now
Bryan Adams & Melanie C - When You're Gone
George Michael & Mary J. Blige - As (cover)
Phil Collins & Phil Bailey - Easy Lover
Robbie Williams & Kylie Minogue - Kids
Whitney Houston & George Michael - If I Told You That

Heavier uptempo (rock-oriented):

A Road To Damascus & Harry Radford - In Retrospect
Ashlee Simpson & Tom Higgenson - Little Miss Obsessive
Distance And Divide & Garret Rapp - Dark Days
Flyleaf & Sonny Sandoval - Something Better
New Found Glory & Patrick Stump - King Of Wishful Thinking (cover)
Simple Plan & Jordan Pundik - Farewell
Too Close To Touch & Kellin Quinn - The Chase

---Three people or more:---

Ballads/etc.:

Az Yet & Peter Cetera - Hard To Say I'm Sorry (cover)
Backstreet Boys, Nsync & More - Let The Music
Blue & Elton John - Sorry Seems To Be The Hardest Word (cover)
East 17 & Gabrielle - If You Ever
Mariah Carey & Boyz II Men - One Sweet Day (cover)
Mariah Carey, Joe & 98 Degrees - Thank God I Found You

Others:

Alex Band, Chantal Kreviazuk & Emmy Rossum - Cruel One
Bruno Mars, Cee Lo Green & B.o.B - The Other Side
Christina Aguilera, Lil' Kim, Mya & Pink - Lady Marmalade (cover)
Fort Minor, Eric BoBo & Styles Of Beyond - Believe Me
Nsync, Mandy Moore, Christian Burns & True Vibe - On The Line