I've seen a few people hype Ogrepon-W as one of the best in the tier, and I'm curious as to what exactly make it that great (or is it not and I've just been deceived.)
Ogerpon-W hits like a truck while having a decent speed tier. It's not bulky but it's not weak to any priority move in the tier so it can usually live a fast hit.
Water + Grass is a bit hard to switch into, mostly due of Ivy Crudgel strong base power + crit chance and Power Whip raw power / Horn Leech recovery. And Ogerpon has a really wide tool of coverage moves at her disposal. Swords Dance also gives her a solid wincon, and she can patch up her speed with Trailblaze.
For dragons, like Roaring Moon, Kyurem or Raging Bolt she has Play Rough, Low Kick for Kingambit, Knock Off for utility, U-Turn for pivoting, Encore for locking sweepers on setup moves or a Gambit into Sucker Punch...
Water Absorb conditions a lot of switch-ins on its team. For example, Primarina won't almost never click Surf aganist an Ogerpon team, so you can switch around Moonblast.
Waterpon in fact it's so good aganist water attacks that it mostly negates the rain matchup by itself. She's also extremely strong aganist stall and once tera is forced by a team mate she can actually 6-0 by herself.
She's good aganist balance, really good in HO with web support... She's basically good in almost any matchup and quite splashable.
Finally, the Sp.Def boost on tera is really helpful aganist stuff like Walking Wake, Iron Moth, special Iron Valiant or Darkrai. It can turn the matchup really quickly.
Waterpon however has her flaws. She's weak to every single hazard, a bit on the frail side and while not weak to a priority
move, she's not good aganist priority itself. She's also ruined by paralysis.