Other then technology (and even then, not by that much) Iran outclasses them in almost every way. Numbers, leadership, economy, national unity, everything. The only thing saving the GCC from total defeat in this scenario is the Gulf itself.
could easily be that i - as a military noob - am just plain wrong but the ...for many years...financially and logistically restrained iran ......in a hypothetical battle between most of the arab world, which seemingly follows Saudi's lead now wherever it goes (Yemen, Qatar....) and a single if strong country, which - i guess - in such a set-up wouldn't even by supported by russia....seems....unlikely to me.
but as i said, maybe my lacking military knowledge is blindsiding me.
