Dollieh Sanctuary

Can Blythe and Pullip share wigs?

Technically yes-ish. Blythe are size 11 and Pullips/Taeyangs are size 10, so if you're shopping around for size 10-11 wigs those ought to fit both fairly well.
The wigs that come on Pullips don't have elastic and basically the cap covers only the crown of the head, so even though they're smaller than Blythe's they should fit on her head alright, and vis versa, just needing some velcro or glue to stay on.

All that said, I've never owned a Blythe and I no longer own any Pullips, so most of my knowledge on the subject of wig sharing is stuff I remember reading on Pullip forums/Requiemart's blog. So take this with a grain of "how faulty is Pandor's memory exactly" salt.

That's fine, I'm on the fence of parting with my Blythe head and one of her wigs but I really like the other one. Looking at the Pullips I like their look a bit better.