Upgrades on partner flights are not a *A benefit. Elites of other members don't even get into United's Economy Plus section of the main cabin. (They did at one point, but that stopped as soon as UA figured out that no other partner has an E+ section that offers a comparable benefit to UA elites.)

I've occasionally gotten operational upgrades due to *G status, but that's a random event, not a right. When they have to move someone forward to make room in back, they often seem to take partner status into account in deciding who that should be. (I say "seem to" because I have no insight into their decision process, but I can't think of any other reason I'd be singled out. It's surely not for my good looks.) In my experience these upgrades are rare, though of course welcome when they happen.