The DPP ladder has improved MASSIVELY since 2017-2018 and you can find alot of amazing players on the ladder. If you are contemplating to start learning DPP OU, now's the time, even from the ladder you can get a good understanding of the meta and fight loads of experienced veterans
Some things I've noticed:
Sub defensive Rotom is increasing in popularity, really good for screwing with choice scarf ttar and pairing it with another elec like agil zap or raikou at the end phase makes it really good. Bait the tar, wisp it if they wanna stay in, checkmate with your 2nd elec lol, too brutal.
Non-LO gengar is AMAZING, goddamn, wisp has shitty accuracy and same with fblast but its so good at dismantling annoying defensive cores and provides you alot of important information about the opps team, you dont have to be able to guess the opps team in dpp to be great, have mons that lure out common Pokemon and that helps you make a solid plan way before endgame as many players usually leave the thinking till.
Been toying with gliscor quite a bit as of late, (2 fangs eq sd, taunt is an option but limits your fire power and using stone edge sucks lol) yache offensive variant. You can run through nido/clef/skarm especially if you use a fire punch slam rachi to burn alot of stuff beforehand.
Morale of the story, sp.def slam jirachi is too good man, why pass up on something that gives you free wins when its legal lol. I've been the biggest Choice band Infernape diehard fan since 2010 but sadly it just isnt performing the same.
Oh and Metagross is the best lead in dpp, change my mind.