Wrath over Bro has some rationale to it, but with the set you're running, why not Golduck? Seems to me that would perform just as well without being a liability vs Psychics
Golduck is already a liability vs Psychics, if I have a Golduck in vs any standard team, the standard will aways go to chansey, starmie or alakazam and block golduck from doing anything. They also have other options like, Jolteon, Cloyster, Lapras..maybe Zapdos.
Poliwrath is better than golduck IMO.
Submission: Makes it possible to KO Chansey when coming in, but because poliwrath also has amnesia which forces the need of them to prevent Poliwrath from boosting up.
Poliwrath has hypnosis: Even if it's not on your set, hypnosis can act as a bluff that you have it.
Fighting type means: earthquake resistance means its similar to exeggutor, which means Poliwrath can come in on Rhydon and force Rhydon to swap, which creates a turn to use one of the following: submission, hypnosis, blizzard, amnesia, hydro pump.
But how do I swap in Golduck???
Is it vs a chansey Ice beam? No.
Is it a starmie blizzard? No.
Is it vs Snorlax? I doubt it.
Is it vs a STAB Exeggutor psychic? Well, theoretically it can, but thats a lot of damage.
Poliwrath isn't fantastic, but might be D-tier, where Golduck is likely a full tier lower.
Amnesia isn't usually OP, Chansey/Starmie/Alakazam block it well enough. Explosion users also prevent it from being a big issue.
Slowbro I'm trying to argue that it isn't even quite OU and should be borderline.
Snorlax is seldom better off with Amnesia.
Golduck is mostly bad...
Poliwrath is mostly bad...
...Mewtwo would be Uber even without Amnesia.
Although I'd be interested in what thoughts are about the move: Growth. Is it ever viable?
Edit: after looking at what has growth is:
Victreebel
Venasaur
Tangela
Parasect
Non of that is viable with growth.
Meditate is ever viable? Is maybe a better question.