With the removal of some of Toxapex's greatest threats, I personally feel as though it has grown too large for its britches. There are other offensive threats that do deal super effective damage, but they haven't the offensive stats of Zygarde and Kyurem Black to really threaten it.
Furthermore, Regenerator provides sustainable healing so long as you have another pokemon to switch to, making any pokemon incapable of dealing reliable 33%+ damage a non-threat, until you factor in the fact that its main set uses recover, healing it even further. Toxic and scald, depending on what you are facing, provide chip damage to whatever opponent you face, and Haze neutralizes any attempts to set up. Lest you forgo Toxic for Knock Off, you now have a way of preventing banded/spec'd pokemon from keeping that monumental 1.5x boost, and deny other pokemon Leftovers or Black Sludge. The latter of those you yourself use to keep the health high in the sky.
It is also a major defensive check/counter to a wide swathe of the meta, such as Urshifu-S and Volcarona, prominent offense-oriented pokemon, as well as most physical pokemon without a SE move, which is rare due to the only weaknesses of Toxapex being Electric and Psychic.
Granted, it does have counterplay in Tapu Koko and Regieleki, but simply having a ground type on your team to support Toxapex, which kazam1228 notes as,
makes those top Electric threats almost a non-issue.
Psychic types like Latias and Alakazam present little issue, because switching to a special wall like Chansey or Clefable act as checks sufficient enough to enable high-end switching, and recover all the damage dealt because of Regenerator, or even have the opponent make a slip, exposing them further.
There is little counterplay that cannot be negated, and because of its defensive nature Toxapex avoids the standard model for banning, which, while admittedly may be misremembered, goes along the lines of "broken offense is more noticeable and apparent". It is my personal belief that banning Toxapex will allow for a better metagame.
Sorry, I forgot to post this right away, but I feel the need to address this.
Tapu Koko and Regieleki are not the only answers to Toxapex, and in fact are some of the worst option available. Counterplay for Toxapex has never been better, so if you are seriously finding yourself lacking any means of handling it here are some cool tips.
Heatran @ Leftovers
EVs: 4 HP / 252 SpA / 252 Spe
Ability: Flash Fire
Modest Nature
- Magma Storm
- Taunt
- Earth Power
- Toxic / Protect / Stealth Rock
Trapper Heatran basically puts your opponent in a very tight bind. Here you have a very powerful Fire type who can put a huge chunk into your team, and you have a perfectly healthy Pex in the back. Your thought is to switch in and eat the hit, right? Well the moment you switch in and get hit by Magma Storm, that's a dead Toxapex, as you get trapped, and get Earth Powered to death. Otherwise your opponent gotta content with trying to eat a Magma Storm, and there is little else can handle doing all a that while being run alongside Toxapex.
Tapu Fini @ Leftovers
Ability: Misty Surge
EVs: 252 HP / 64 SpD / 192 Spe
Timid Nature
- Moonblast
- Scald
- Taunt
- Nature's Madness
Or
Tapu Fini @ Leftovers
Ability: Misty Surge
EVs: 252 HP / 200 Def / 56 Spe
Bold Nature
- Calm Mind
- Taunt
- Draining Kiss
- Surf
Tapu Fini screws around with Toxapex fairly well, and basically turns non Toxic Spikes variants into complete fodder. Utility sets stop Toxapex from doing its most important role in forcing progress while walling the opponent, by preventing Status, while chunking its HP with Nature's Madness. Calm Mind sets take this one step further, and turn Toxapex into setup fodder, allowing it to clean up games once played right.
Latios @ Choice Specs / Life Orb
EVs: 252 SpA / 4 SpD / 252 Spe
Ability: Levitate
Timid Nature
- Draco Meteor
- Psyshock
- Mystical Fire / Aura Sphere
- Trick / Recover
Latios is one of the most fearsome wallbreakers in the tier following the departure of Kyube and Zggy, and its not hard to see why. Its Draco Meteors even sting resiats, and having a powerful Psyshock that blows back "special walls" with ease. I am genuinely shocked that you would confidently claim that Latios is of little issue, as none of the Pokémon (including Toxapex) you mentioned can switch in on Psyshock. Worse than that, Specs has the additional tool of Trick, which turns Toxapex and the aforementioned Blissey into deadweight, and makes Clefable much easier to play around.
+ Future Sight
Urshifu @ Choice Band
EVs: 252 Atk / 4 Def / 252 Spe
Ability: Unseen Fist
Jolly Nature
- Wicked Blow
- Close Combat
- U-turn
- Poison Jab / Sucker Punch / Iron Head
This is a tried and true method of shitting in balance cores, and as my comrade
Jordy said a few pages before, this playstyle has 100% not lost its efficiency. Its pretty simple. Set Future Sight, get in Urshifu, and click the appropriate STAB and watch as something dies. If Toxaoex is your prominent Fighting resist, as it usually is, you usually either sack Toxapex, or sack a team mate to bring it in later, only for Urshifu to repeat that cycle a few turns later.
All of the threats I have mentioned are great Pokemon and would do exactly what I described regardless of whether or not Toxapex is in the game, so you don't gimp yourself by using these mons. I haven't even brought up several more niche (albeit more unreliable) ways of handling Toxapex, such as Tapu Lele, Calm Mind + Thunderbolt Clef, SubWisp Spectrier, Hydreigon and Nidoking, which are not top tier atm or are more prone to losing, but they still get the job done.
Toxapex is a fantastic Pokémon, helping us keep several threats at bay from destroying teams, but is by no means a broken threat in the Crown Tundra metagame. Quite honestly, if you are consistently losing to Toxapex in THIS metagame, maybe its not the problem here