ZU Sun Slammer 2.0

Leafeon @ Life Orb
Ability: Chlorophyll
EVs: 252 Atk / 4 SpD / 252 Spe
Adamant Nature
- Leaf Blade
- Solar Blade
- Knock Off
- X-Scissor

Silvally-Ground @ Ground Memory
Ability: RKS System
EVs: 252 Atk / 4 SpD / 252 Spe
Jolly Nature
- Flame Charge
- Swords Dance
- Multi-Attack
- Rock Slide

Torkoal @ Heat Rock
Ability: White Smoke
EVs: 88 HP / 252 Atk / 136 Def / 32 SpD
Brave Nature
- Earthquake
- Stealth Rock
- Heat Crash/Flame Wheel/Superpower/Lava Plume
- Sunny Day

Lapras @ Assault Vest
Ability: Water Absorb
EVs: 172 HP / 16 Def / 252 SpA / 64 SpD / 4 Spe
Modest Nature
- Solar Beam
- Freeze-Dry
- Surf
- Ice Shard

Magmortar @ Choice Specs
Ability: Flame Body
EVs: 252 SpA / 252 Spe
Modest Nature
IVs: 0 Atk
- Overheat
- Weather Ball
- Focus Blast
- Thunderbolt

Meowstic (M) @ Choice Scarf
Ability: Infiltrator
EVs: 56 HP / 252 SpA / 136 SpD / 64 Spe
Timid Nature
IVs: 0 Atk
- Psychic
- Psyshock
- Energy Ball
- Dark Pulse

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Notes:
Meowstic is ev'd to outspeed + 2 Omastar and OHKO it with Energy ball. The rest goes into SpDef to sponge. [03/05/2021: Ev's have een changed to 56 HP to hit 303 hp, still max SpAttack, 136 SpDef, and 64 Speed. The extra 20 points of speed are crucial to outrun accelgor.
Meow can also switch into a fighting move if necessary, as nothing else on the team resists.
I will also note that since most people expect prankster sunny day, you can lure them into a false sense of security and blast them turn one. Energy Ball vs. Dugtrio (another thing this set outspeeds) being a great example of one potential victim. I could imagine a toxic spiker like Garbodor or Qwilfish. Psychic does at least 70% to Max HP, 0 SpDef Garbodor, while actually doing 85-100% to 0 HP, 0 SpDef Garbodor. Yep, just did some more calcs and it turns out Qwilfish gets smoked by psychic unless they run Max HP and a significant chunk of SpDef. Like, 148 SpDef to be exact, and that's just to live at 1%!

Torkoal:
Heat Crash is so-so. Most of the time it's unfortunately at 40 base power, but when a rotom switches in thinking it has a free switch it gets absolutely crushed
Example: 252+ Atk Torkoal Heat Crash (120 BP) vs. 0 HP / 0 Def Rotom-Fan in Sun: 229-270 (95 - 112%) -- 68.8% chance to OHKO
Now, obvs if they have bulk, this doesn't do as much, but the point remains that heat crash *can* have value. You can opt for less attack evs and go lava plume if you like though. The burn chance is quite nice.
I used to run Explosion over stealth rock, but I found myself never clicking it and sorely missing a way to punish opposing switches.

Magmortar:
Overheat absolutely nukes everything. Weather ball is nice when you can use it, but I almost prefer flamethrower more. Then again, with the way I play it, magmortar is in and out a lot and doesn't even mind the -2 SpAttack when it does stay in, so weather ball is nice for coverage in other weathers or more basepower if compared to flamethrower in sun. I chose t-bolt and focus-blast instead of scorching sands because I like to miss moves and because of ice and dark types I guess :)

Leafeon:
With Magmortar being something of a special wallbreaker, you could consider Leafeon to be the physical counterpart. Solar blade does massive damage and I honestly recommend it over clicking knock off in most scenarios simply because you'll chip your opponent so heavily (as long as they don't resist grass) that you'll be able to KO them with something else on the team.

Lapras:
Lapras is a fantastic special wall with water absorb and assault vest. Add to that the fact that it learn Solar Beam and you've got yourself a wonderful special wallbreaker that synergizes nicely with Magmortar's coverage. Freeze-dry is fantastic, couple it with ol' reliable surf and you hit most things Mag doesn't. Ice shard is nice to pick off things like Substitute, Hone Claws, Scale-shot, Earthquake Gabite (mentioned only because I actually ran into it myself during testing), and focus sashed mons like Dugtrio or Accelgor.

Silvally:
Despite not having U-turn, you can reliably get this bad boy in with prediction and do some good work with Quake-Slide + Flame Charge and SD.

Replays:
https://replay.pokemonshowdown.com/gen8zu-1294692359-6oncvwargukoi9ja4h8ba3vwlb3htrvpw