Gaga - 3 (Pop Vocal Album, Pop Vocal Performance, and Traditional Pop Vocal Album)
Kelly Clarkson - 3 (Pop Vocal Album x 2, Pop Vocal Performance)
Beyonce - 1 (Pop Vocal Performance)
Xtina - 4 (Pop Duo/Group x 2, Pop Vocal Performance x 2), also a Latin Grammy
Amy W. - 3 (Pop Vocal Album, Pop Vocal Performance, Pop Duo/Group)
Joni M - 3 (Pop Album x 2, Pop Instrumental)

I'll update the OP with others if there are any

None, my fav has never even been nominated despite numerous submissions.

Beyoncé has one pop Grammy, from five nominations.

Beyonce has a Best Pop Vocal Performance Grammy for Halo.

a shame Some Hearts deserved a nom, and I'm sure plenty of others over the years too!

There's a Place for Us was so robbed.

5

Best Pop Collaboration (Lady Marmalade)
Best Pop Vocal Album (Mi Reflejo) Latin Grammy
Best Pop Vocal Performance (Beautiful)
Best Pop Vocal Performance (Ain't No Other Man)
Best Pop Duo/Group Performance (Say Something)

Best New Artist ✔
Best Pop Vocal Album ✔
Record of the Year ✔
Song of the Year ✔
Best Female Pop Vocal Performance ✔
Best Pop Duo/Group Performance ✔

3

She won Best Dance Recording the year after it was moved from the pop field to the newly created dance field, so zero.

Rihanna - 0
but she won "Best Dance Recording" with OG (ITW) and that's basically a pop catrgory since lots of pop songs won this category.

It's not but she should have a pop win in a few years

3

Three.

Adding Queen Joni M to the OP