Just Dance 3

I found this one pretty simple
It also stacks with the 2 other duet related achievements Ace pair Bronze and Silver

You need to pick a song which only has 2 parts(2 trainers)

Can be done on easy so i recommend easy unless you and your partner are good

Then simply grab a friend and dance,on easy it only tracks your arms so it's a piece of cake if you choose the right song

I'd recommend Something stupid by Robbie Williams and Nicole Kidman and remember you don't have to dance together like they do,just mimic their upper body moves which are really slow and repetitive
If you're struggling with this song LitaOsiris suggests Da Funk as an easy alternative

It shouldn't take too many attempts with the song Something Stupid,i got this and the other 2 duet achievements on the 1st attempt and i can't even dance

Good luck and feel free to comment or recommend easier songs

edit:i'm not sure if short song mode counts or not but it seems to count for most other achievements,so if anyone unlocks it on short song mode let me know and i'll update the solution.