You'd get chickens that have a crest, but not nearly the size of the normal Polish crest. I had a batch of half Polish hatch out last August. Thank goodness only one is a cockerel. Have to say that he's the ugliest chicken I have ever seen with his thin messy crest.
Glad you could join us here! You would just have cross bred chicks and with your roo already been cross bred it's hard to predict what kind of chicks you would end up with. I crossed a frizzle polish with a hybrid hen and the resulting chicks were very unique in their appearance with only a very limited crest and not the vaulted skull that a pure bred polish has.
Good luck if you do decide to hatch some of these eggs and enjoy BYC
As you have already received some good advice/responses I will just add best wishes to you and your flock.
I hope you enjoy being a BYC member. There are lots of friendly and very helpful folks here so not only is it overflowing with useful information it is also a great place to make friends and have some fun. Unlike non chicken loving friends, family and colleagues, BYC’ers never tire of stories or pictures that feature our feathered and non feathered friends
Welcome to BYC!
As noted above, it is difficult to predict just what would come of your proposed cross - and it is likely that even within the same clutch from this pairing you would end up with a variety of final outcomes in appearance, with different degrees of cresting, overall plumage pattern, etc- the only sure way to determine what you get is to go ahead and hatch out a batch or two of chicks, but be sure you have a plan in place for what to do with all the resulting birds before you set those eggs.