IMO the only thing that makes Sun/Rain broken is Sableye and possibly Uxie. Sableye really needs to GTFO of RU. Even thou it has a chance of becomming UU, it should really just get moved to BL2 as soon as possible. The fact that it wrecks any physical sweeper that is not Floatzel or fire type is just rediculous.. And priority sun/rain is way too good for RU. Getting swept by a sableye with no attacking moves just breaks peoples heart! It needs to go!
I'm not really sure about Uxie.. It's good for making weather and just U - Turning out, but easily crippled by Taunt and Trick. If Uxie were banned, people would just use Mespirit, so I believe that it would be a pretty pointless thing to do.
When it commes to sun sweepers, the only ones that MIGHT be too good for RU is Charizard and Sawsbuck. Everytime it commes in and it's sun, it's like you have to sack something, which is why I believe so many people complain about it, but it's kinda the same in OU. If Terrakion or Latios get a free switch in, you pretty much have to sack something, just to revenge them and they're not deemed broken there (at least not Latios). However, What makes me believe that Charizard is not broken, is the fact that after SR and and solar power, any sucker punch/ strong Quick Attack/Aqua Jet will kill it, and Charizard aint got no choice but staying in as it will die with the next switch in anyway. Very few of the Sun teams I've faced and made myself have had space for a spinner. The only option I've found is Sunny day/Rapid spin Claydol, but it's bad. Spinning in RU sucks at the moment, because you're facing a sableye like every 3rd match.
I'm not gonna say too much about Sawsbuck, as I've only faced one in the sun, however with it's great speed, great coverage and access to SD, I believe it deserves to be tested. Especially seing that it will most likely become NU. Still it's walled by steelix (Jump kick doesn't kill after a SD and you can just roar it away) and checked by Chice scarf Accelgor (which have gotten a lot of good words in this sub forum).
It would be great if anyone could bring calcs on how much final gambit/ bug buzz does to standard Sawsbuck.