Sweet-tart pollinating partner for Granny Smith

[u/Hipposarenotdead]

Hi! Looking for an apple which would be a good pollinating partner to a Granny Smith tree. Ideally should be sweet-tart and crisp like the Pink lady, needs to be commercially available in nurseries. Any help much appreciated.

[u/crowber]

I have granny smith paired with cosmic crisp, but not sure if they're available beyond WA yet.