Gen 8 is running at a much lower power level than gen 7 was. It's slower and MUCH weaker. In the past Specs 1.5x Psychic wasn't as crazy as say, +2 Kartana using a Z move or Mega Medicham jumping really high. Yes terrains were nerfed but even considering that the Tapus are going to do more damage than they would have in the previous gen. Tapu Lele 2HKOs almost every single Pokemon in OU right now with Specs Expanding Force + Moonblast. Even Chansey dies in two hits after Stealth Rock, or you cleanly 2HKO it with Psyshock. Even Specially Defensive Ferrothron runs the risk of a OHKO after Stealth Rocks from Focus Blast. Lastly Pursuit is gone to picking it off after it gets locked into something isn't an option.
It's about to jump a HUGE amount, as many of those things that gave such a huge power level are coming back. Like I said, all this you mention is prediction-heavy and you can end up doing very little.
I can see it being handled kinda similar to Urshifu: scout the Choice lock, bring in the resist/immunity. You keep saying how it 2HKOs this and KOs that but the only way that happens in practice is if you get your predictions dead-on. Sure it's strong, but is it that much more stronger than Urshifu's Wicked Blow? Or Magnezone's Analytic Thunderbolt? It has literally no way to break a healthy Celesteela without HP Fire, and Celesteela carries Protect as standard to gain extra recovery, which also lets it stall out Psychic Terrain and/or scout its Choice lock. IMO the set Lele want a to run is going to be Life Orb so you can change up your moves but that causes it to miss out on several benchmarks eg: It always 3HKOs standard Corviknight.
252+ SpA Choice Specs Tapu Lele Expanding Force (120 BP) vs. 248 HP / 232+ SpD Celesteela in Psychic Terrain: 153-180 (38.5 - 45.3%) -- guaranteed 3HKO after Stealth Rock and Leftovers recovery
And the lack of Pursuit trapping hasn't broken Aegislash, Zam or Gengar, three mons who have also had movepool buffs this gen (I know Aegi got nerfed, but it would be Uber if it hadn't). Do we really need to be able to Pursuit trap Nasty Plot Gengar? Besides, Lele is neutral to Dark, so it's no more vulnerable to Pursuit trapping than any other average mon, and I've never heard anyone discuss Pursuit trapping keeping Lando-T or Kartana in check.
Basically, if it turns out to get Mystical Fire, then we've got an issue. Until then, give it a chance lol.
252 SpA Choice Specs Tapu Koko Thunderbolt vs. 0 HP / 0 SpD Mew: 265-313 (77.7 - 91.7%) *with gen 7 electric terrain
252 SpA Choice Specs Tapu Koko Rising Voltage (140 BP) vs. 0 HP / 0 SpD Mew in Electric Terrain: 358-423 (104.9 - 124%)
That's a 35% damage increase. Also Koko has 130 base speed and a good movepool including Close Combat.
Yes, Koko has got buffed. That's the only reason I'm willing to discuss its existence without inserting a redirect tag to Dragapult. But I think your own sentence holds the clue as to Koko's problem. Isn't Close Combat physical? And isn't Rising Voltage special? Are you really going to be able to go mixed with enough investment to make those physical moves meaningful, and still be able to make those impressive on-paper calcs play out?
But there's more than a few problems with Koko. Oh dear, it appears this mon hits like a wet noodle when clicking anything but an E-Terrain-boosted move (something that was also true last gen). But the biggest issue for it? No Hidden Power Ice. How is Koko meant to pressure any Ground types without HP Ice? Especially one mon that may or may not be on 1/3 post-DLC teams or something like that...
252+ SpA Choice Specs Tapu Koko Dazzling Gleam vs. 0 HP / 0 SpD Landorus-Therian: 208-246 (65.2 - 77.1%) -- guaranteed 2HKO after Stealth Rock (Scarf Lando-T can hard switch into anything it does and OHKO it.)
It does get Grass Knot, but even Specs Modest Grass Knot has very disappointing damage output when your attacking stat is as low as Koko's SpA.
252+ SpA Choice Specs Tapu Koko Grass Knot (60 BP) vs. 0 HP / 0 SpD Excadrill: 124-146 (34.3 - 40.4%) -- 47.8% chance to 3HKO after Leftovers recovery (Just in general Koko is going to be dead weight against every Sand team.)
I think overall Koko's best set is going to be a Boots pivot set much like Dragapult and Zeraora.
Tapu Koko @ Heavy-Duty Boots
Naive Nature
Ability: Electric Surge
EVs: 252 Atk / 4 SpA / 252 Spe
- Rising Voltage/Wild Charge
- Close Combat
- U-turn
- Play Rough
Rising Voltage doesn't need to be absurdly invested to put dents in offensive teams, and Koko has 0 chance of being a serious wallbreaker against sturdy backbones. It just does wayyyy too little when clicking moves not called Rising Voltage and struggles too much with Grounds.