Transferring advice in Illinois

Posting for my boyfriend. He is currently an apprentice out of a local downstate. I’m looking for jobs in Chicago/surrounding suburbs, and he’s planning on moving up here soon. We’re wanting to know more about the process of transferring from a smaller local downstate to a bigger local in the Chicago area (150, 701, 461, 117 - but not 134) as an apprentice. If anyone has any info about that, please share! Or, if anyone has experience transferring as a journeyman after topping out, that would be super helpful as well. Thank you!!