G: Yes. The conflicting information makes sense because several different things are overlapping, but they do not all carry evolution moves. I checked the current schedule and the official event announcements.

For this week, September 14–20, 2026, the important distinction is:

Pokémon / event	What's special	Evolve now for legacy move?
Dynamax Rhyhorn	Dynamax debut; available in Max Battles all week	NO — no Rock Wrecker bonus
Gible → Garchomp	Community Day Classic was Sept. 12	TOO LATE — Earth Power window ended Sept. 12 at 9 PM
Friede's-goggles Charmander	New costume family starting Sept. 16; Spotlight Hour Sept. 17	No announced Blast Burn evolution bonus
Mega Venusaur	Returns Sept. 16	No Frenzy Plant evolution bonus
Mega Staraptor	New Mega debuts Sept. 19	Not an evolution-move event

So the particularly important answer for you is: do not evolve a good Dynamax Rhyhorn into Rhyperior expecting Rock Wrecker. Dynamax Rhyhorn's debut does not currently reactivate Rhyperior's Community Day move. Rock Wrecker remains an exclusive/legacy move. citeturn2view1turn3search3

What's actually happening this week

Dynamax Rhyhorn is probably the thing most worth paying attention to right now. It debuted Monday and continues in Max Battles through September 20. The Monday 6–7 PM concentration is over, but Rhyhorn remains in the week's Max pool. citeturn2view0

That creates a somewhat annoying decision. If you catch an excellent Dynamax Rhyhorn, I'd preserve it as Rhyhorn for the moment if your ultimate goal is a Rock Wrecker Dynamax Rhyperior without spending an Elite Charged TM. There is no advantage this week to rushing the evolution. Rhyperior with Rock Wrecker is substantially more interesting than ordinary-moveset Rhyperior, and Pokémon GO has previously rerun old Community Day moves during special events. citeturn3search3turn3search9

The Gible Community Day Classic is probably another source of the conflicting reports you're seeing. That happened Saturday, September 12. Evolving Gabite produced Earth Power Garchomp, but only through 9:00 PM local time on September 12. That window is finished. citeturn0search3turn3search5

Starting tomorrow: Pokémon Horizons

From Wednesday, Sept. 16 at 10 AM through Tuesday, Sept. 22 at 8 PM, the Pokémon Horizons celebration starts. The major new collectible is Charmander wearing Friede's goggles, and unlike many costume Pokémon, this one can evolve into Charmeleon and Charizard while retaining the costume. citeturn2search1

There is also an unusual Thursday Spotlight Hour, Sept. 17, 6–7 PM, featuring the costumed Charmander with 2× catch Stardust. citeturn2search7

But here's the trap: I find no official announcement that evolving it gives Blast Burn. So don't confuse "special Charmander that can evolve" with "Community Day evolution window." They're separate things.

The Horizons event also gives rotating wild spawns:

5 AM–5 PM: Fidough, Wattrel and others, with Chansey as a rarer encounter.
5 PM–5 AM: Eevee, Hatenna and others, with Rockruff as a rarer encounter.
Increased Kecleon appearances at PokéStops.
Pikachu wearing Cap's hat returns.
One-star raids have Cap Pikachu; three-star raids include the costumed Charizard, Meowscarada, Skeledirge and Quaquaval. citeturn2search1

Those event encounters can also have Special Backgrounds, including the raid Pokémon and costumed Charmander line where applicable. citeturn2search1

Raids / Mega stuff worth knowing

Zacian leaves five-star raids September 16, replaced by Zamazenta, with Zamazenta Raid Hour Wednesday from 6–7 PM. Mega Beedrill and Mega Houndoom also leave, replaced by Mega Venusaur. citeturn2view0

Then Saturday, September 19, 2–5 PM, is Super Mega Staraptor Raid Day. Mega Staraptor debuts, shiny odds are boosted, and there are up to five additional free raid passes. citeturn2search7 The new Mega system also means Super Max Megas can eventually gain their additional Mega-only Charged Attack; that's a different mechanic from Community Day/legacy evolution moves. citeturn0news6

So, specifically for your evolution pile

If you're sitting on Pokémon thinking, "Should I evolve this before this week's opportunity disappears?":

There is currently no active general legacy-move evolution window this week. Gible's Earth Power window has already ended. Dynamax Rhyhorn does not currently give Rock Wrecker Rhyperior. Friede Charmander does not currently give Blast Burn Charizard. Venusaur's appearance does not reopen Frenzy Plant.

The one I would especially not prematurely evolve is a high-quality Dynamax Rhyhorn. Catch several this week, compare IVs, and park the promising ones. You can always make the Rhyperior later; you can't unevolve it if a future Rock Wrecker evolution event appears.

urlOfficial Pokémon Horizons event detailsturn2search1
urlFull September 14–20 scheduleturn2search7

If you'd find it useful, I can also check all of the Pokémon currently obtainable this week against their historical legacy/evolution moves and give you a short "CATCH NOW / EVOLVE NOW / SAVE UNEVOLVED" list. That would catch things like Rhyhorn where the week's event itself doesn't make the legacy-move issue obvious.

I can also monitor Pokémon GO announcements and alert you when Niantic opens an evolution window for things like Rock Wrecker Rhyperior, Meteor Mash Metagross, Hydro Cannon starters, etc.