Are you permitted to forward the reviews from a rejected manuscript when submitting to a new journal?
I have done this a couple of times (but not always going down in the journal hierarchy). In my cover letter I indicated that "the paper was previously submitted to [blah], but was rejected because [...]. A copy of the report can be obtained by writing to [editor name]."

The motivation for not including the copy of the report is that it keeps me honest. I can't just select the bits I like.

I have never had any problems with this approach, and I believe it to be the right thing to do. It saves editors' and referees' work.