"Smogon doesn't end by burning itself. It ends with Toxapex." - Fireburn 2017
Toxapex's unique typing, great defensive stats, and access to utility moves such as Toxic Spikes, Scald, and Haze make it a valuable Pokemon to have on defensive teams. It should be used as a physically defensive pivot to check dangerous threats such as Mega Lucario, defensive Ho-Oh, and Marshadow. Toxapex's access to both Regenerator and Recover makes (access to is singular) it a fairly easy Pokemon to keep healthy while staying in and checking threats or switching out accordingly. However, its nasty Ground-type weakness does leave it vulnerable to Primal Groudon, Zygarde-C, and Arceus Ground, as Toxapex can only indirectly damage them through Toxic Spikes. Primal Groudon is even worse for Toxapex, as it completely nullifies Scald. Furthermore, Toxapex's passive nature also gives way to it being a Pokemon that Mega Gengar can switch into and trap. Toxapex must also be very careful against some of the Pokemon it aims to check because they can carry deadly attacks that can overwhelm it such as Marshadow using Bulk Up and Soul-Stealing 7-Star Strike. Toxapex also faces competition from Tentacruel, as Tentacruel has access to Rapid Spin, is faster than other defensive threats, and has better special bulk.
move 1: Toxic Spikes
move 2: Scald
move 3: Recover
move 4: Haze
item: Rocky Helmet / Shed Shell
evs: 252 HP / 252 Def / 4 SpD
Toxic Spikes is Toxapex's best method of wearing down many grounded Pokemon that don't use Rest, lack access to moves such as Refresh and Aromatherapy, or do not have a Poison or Steel typing. A single layer of Toxic Spikes is the most sufficient method of beating most offensive archetypes; however, a second layer can also be used against bulkier teams that may attempt to keep their Pokemon in for more than three turns. Toxic Spikes will be mostly effective against Primal Groudon, non-Aromatherapy Xerneas, various support Arceus formes, and Primal Kyogre. Scald is mostly used for its 30% chance to burn foes such as Marshadow and Mega Lucario while also making Toxapex less vulnerable to Taunt. Recover is necessary to keep Toxapex as healthy as possible to continually check defensive Ho-Oh and non-Bulk Up Marshadow. Haze is a great fourth move to eliminate boosts from Z-Geomancy Xerneas and Swords Dance Mega Lucario.
Maximum HP and Defense investment allows Toxapex to continually check physically offensive threats with maximum potency. Rocky Helmet is the best item for Toxapex due to its rather passive nature and allows it to indirectly damage Mega Lucario, Marshadow, and defensive Ho-Oh when hit by their contact attacks. Shed Shell is a viable option over Rocky Helmet, as Mega Gengar has nothing to fear from Toxapex outside of Scald's burn rate. Shed Shell also allows Toxapex to escape from Dugtrio, which can OHKO Toxapex after some chip damage with STAB Tectonic Rage.
Toxapex should be used as a physically defensive pivot that can switch into dangerous physical attacking threats such as Mega Lucario and non-Bulk Up Marshadow while also being able to absorb Toxic Spikes for its own team. Toxapex can take advantage of some passive Pokemon such as Arceus-Water and Arceus-Fairy thanks to its typing, recovery, and great bulk. Toxic Spikes is rather easy to set up, as both Arceus formes are forced to either use Defog or potentially cripple one of their teammates by switching out. Though Toxapex is fairly bulky, it still can be easily overwhelmed by boosted Z-Moves such as Never-Ending Nightmare from Arceus-Ghost and Soul-Stealing 7-Star Strike from Marshadow. Toxapex is still limited against stronger threats such as physically offensive Ho-Oh and Mega Salamence, so it should not be used as the end-all physically defensive wall for these particular Pokemon. If possible, try to bait out their moves and switch into Pokemon that can easily survive the attack or potentially sacrifice a teammate when absolutely necessary. Be prepared to make educated double switches when Toxapex's checks and counters such as Primal Groudon arrive, as they are almost impossible for Toxapex to touch.
Ho-Oh is an excellent teammate to check the majority of Primal Groudon and non-Swords Dance Arceus-Ground sets. Ho-Oh greatly appreciates Toxic Spikes support to make bypassing both Primal Kyogre and Primal Groudon easier. Support Arceus-Ground is also a great middle ground to handle Primal Groudon as well as Zygarde-C, though Arceus-Ground has to be careful of Dragon Dance variants if it is low on health. It can clear Spikes and Stealth Rock on Toxapex's side of the field, while Toxapex can handle some of the Pokemon that may take advantage of or overwhelm Arceus-Ground and clear Toxic Spikes on its side of the field. Unfortunately, Toxapex fully investing in physical bulk leaves it a little more vulnerable to special attacks. Chansey is a reliable partner that appreciates Toxapex checking some of the Fighting-types in the tier and can handle Xerneas and Lunala. Some of the Pokemon that Toxapex can lose to, such as offensive Ho-Oh, Yveltal, and Mega Salamence, can be easier to check with Stealth Rock support from Pokemon like Tyranitar and Primal Groudon. Tyranitar has the perk of being able to have a reliable STAB Rock-type attack as well as STAB Pursuit to trap Mega Gengar lacking Will-O-Wisp. Steel-types such as Ferrothorn and Celesteela are great partners alongside Toxapex as well. Celesteela tackles non-Gravity Arceus-Ground and checks Excadrill. Ferrothorn has great type synergy with Toxapex and is able to provide Spikes support. Both of these Pokemon appreciate Toxapex being fairly reliable for handling Ho-Oh and most variants of Mega Blaziken without too many issues. Both Giratina formes can be great assets alongside Toxapex. Giratina is a great defensive Pokemon that can support its team with Defog while crippling foes a little more reliably with Will-O-Wisp if necessary. Having access to Dragon Tail also forces the foe to switch into Toxic Spikes. Mega Sableye is a reliable partner that can bounce back entry hazards to keep Toxapex as healthy as possible while also being another check to Mega Gengar.
Wacan Berry lets Toxapex act as an emergency Xerneas check, but outside of that circumstance, it has little use whatsoever. Toxic cripples Ho-Oh and Yveltal, since they are immune to Toxic Spikes, but in most cases, the utility of Toxic Spikes is heavily preferred; thus, Toxic would only be an option over Haze. Lacking Haze makes Toxapex weaker to Mega Lucario and Bulk Up Marshadow, though. Ice Beam helps Toxapex a bit more versus Mega Salamence, Rayquaza, and Zygarde but is otherwise inferior to Scald in most cases. Finally, Black Sludge gives Toxapex passive recovery, though Rocky Helmet and Shed Shell are far better options for Toxapex.
Checks and Counters
**Mega Gengar**: Mega Gengar traps Toxapex and only fears repeated Scalds. It has various tools to overcome Toxapex such as Taunt and Will-O-Wisp + Hex. Mega Gengar also clears Toxic Spikes when it switches into them. Be advised that Shed Shell Toxapex can freely switch out from Mega Gengar.
**Ground-types**: Primal Groudon, Zygarde-C, and Arceus-Ground are the three big Ground-types that Toxapex has to avoid at all costs. Though Toxic Spikes can be bad news for Primal Groudon and Arceus-Ground, Zygarde-C can use Rest to remove the poison while firing off STAB Thousand Arrows. Primal Groudon's Desolate Land completely nullifies Scald, and Toxapex is vulnerable to Precipice Blades. Arceus-Ground can use Judgment to scare Toxapex and Defog to keep Toxic Spikes from the field. Excadrill and Dugtrio are also bad news for Toxapex, as their STAB Earthquakes will do a tremendous amount of damage to Toxapex. Excadrill can remove Toxic Spikes with Rapid Spin, while Dugtiro prevents Toxapex from switching out, though it should be careful of Shed Shell, as it lets Toxapex switch out freely from Arena Trap.
**Psychic-types**: Deoxys-A, Lunala, Tapu Lele, and Mewtwo can easily overwhelm Toxapex with strong STAB Psychic-type attacks. Toxapex does pitiful damage to the majority of these Pokemon with Scald, though it does threaten to remove Lunala's Shadow Shield and cripple Mega Mewtwo X. Tapu Lele and Mewtwo can also carry Taunt to create major disruption for Toxapex.
**Mega Sableye**: Mega Sableye can redirect Toxic Spikes to Toxapex's team, which can be bad news if Toxapex's teammates are grounded Defog users. Though Mega Sableye cannot do much back to really threaten Toxapex, Will-O-Wisp can cripple Toxapex defensively.
**Mega Salamence**: Mega Salamence sets with Dragon Dance and Facade fear nothing from Toxapex, as a Scald burn powers them them up. After Mega Salamence is burned, +1 Facade does a tremendous amount of damage to Toxapex.
**Strong Special Attackers**: Though Toxapex has a rather high Special Defense stat, it can still be overwhelmed by Pokemon such as Yveltal and Thunder Primal Kyogre. Xerneas can switch into Toxapex and threaten it out with Thunder, though setting up Geomancy is rather dangerous due to Haze.
**Electric-types**: Zekrom, Arceus-Electric, and Tapu Koko are Pokemon that Toxapex does not enjoy facing, as they do significant damage to it with their Electric-type STAB moves. Zekrom must be wary of switching into Toxapex, though, as Scald's burn cripples it.
**Ho-Oh**: Choice Band Ho-Oh can easily switch into Toxapex and threaten it with either STAB Brave Bird or Earthquake to bypass Rocky Helmet. Life Orb Ho-Oh can overcome Toxapex if Toxapex directly switches into it, as Life Orb Brave Bird is a 2HKO after Stealth Rock or a layer of Spikes; however, Ho-Oh cannot directly switch into a healthy Toxapex or one that will likely use Recover the same turn it switches in, as Ho-Oh can be easily stalled out by Life Orb recoil, Brave Bird recoil, and Rocky Helmet damage from Toxapex.