I haven't been able to track this down. The closest I came was this: Crabapple Pollenizers for Apples. I'd prefer to give you the answer here, but I think the best I can do is suggest you call the info line at the bottom of that factsheet page.
Pollination of flowering crabapples doesn't seem to be a concern, as though most are self-compatible. When I've seen one that wasn't fruiting much or not at all, I figured it wasn't a fruitful cultivar. However, that may not be true at all! Maybe most or some are self-compatible (self-fruitful), and some aren't. Nowadays, in my area at least so many are planted there would seem to be ample opportunity for crossing - both with other flowering crabapples and with orchard apples.
