I don't know why there are so many misconceptions here...
First, chemical structure of nandrolone (deca) resembles progesterone which may stimulate progesterone receptor.
Progesterone without estrogen can not do anything (If estrogen level is ZERO, progesterone can not induce gyno). However, progesterone can also contribute to bloating without the presence of estrogen. If estrogen is high, slight elevation of progesterone will cause gyno.
The drug available that block progesterone is RU-486 and NOT bromocriptine.
Deca also has prolactin activity (similar to trenbolone) which can be blocked by dopamine agonist like bromocriptine or cabergoline.
Deca can also be converted to estrogen via different pathway where aromatase enzyme is not involved. So, nothing can actually decrease the amount of estrogen from deca. I think the best way to minimize estrogen side effects is by using nolva.
Arimidex/Femara/Aromasin --> anti aromatase, so should be used for ALL testosterone-based AAS.
Nolvadex --> Estrogen receptor blocker
Bromocriptine/Cabergoline --> block prolactin side effects from deca or trenbolone