Sun is still completely viable, and in PGL Sun is boosted to an insane degree by the return of Tangela. Tangela's actually 4th on usage stats and Vulpix close behind, at around 30% each (34% for Tangela). In standard Queenlucy's (sorry, Mad0ka) sun team is legendary, and sun is overall still effective.
Other weathers are less so. Rain teams exist, but since they must be set up manually they're uncommon and not actually too effective. Some Pokemon with Swift Swim do run Rain Dance as one of their moves though.
Hail "teams" don't really exist. Amaura with Snow Warning isn't overly uncommon, however, since it lets it BlizzSpam, stop Sun teams, and break sturdy.
Sand teams are pretty uncommon. They exist, but I haven't run into one in a long time. Hippo is useful beyond sand, and Drilbur is still threatening with Sand Rush, but it's not fantastic. PGL-wise, you're got issues with the Most Dominant Mon in Sneasel hitting you in the face with lots of ice.
In terms of abusing evasion chances, I wouldn't suggest it. Snow Cloak is only in the hands of Cubchoo and Swinub (and they're sorta ehhh...). Sand Veil is better though. It has Gligar, who doesn't have much of a better ability to run. Gligar's annihilated by Sneasel though.
And welcome back!