Pokémon GO bosses come in two varieties: raids and Team Go Rocket fights. Here we're going to mention the boss fights that can make a player experience hell itself.
Note that PoGo has constant balancing updates, and newer mons become available with every update, so better counters can nullify these threats. Bear in mind, however, that this still means that newer examples (and updated old examples) may appear as well.
- Tier 3 Claydol. While it has a CP of merely around 13000, it has one of the highest defense of any raid boss, to the point that Kyogre and Gengar need to be nearly maxed out in order to even have a chance. Other high tier counters such as Shadow Ball!Mewtwo, Tyranitar, Gyarados and Sceptile need weather boost in order to even succeed, despite having high DPS. While the 2019 Hoenn event made things easier due to the raid boss HP boost afterwards, it went back to its past difficulty and your non-Kyogre counters, including Giratina Origin and Mamoswine need to be maxed out in order to even stand a chance.
- Early on, Tier 3 Jolteon. While this might seem like a typical high difficulty tier 3 raid boss at first, it only has a sole weakness to ground. The problem? Back then, Ground moves were limited to Earthquake (And later Bulldoze on Mamoswine) and were incredibly slow and inefficient, so most of the time you are barely doing any damage and you will time out. Groudon makes this slightly better, although you will still need to have them maxed or near-maxed out in order to see any visible result.
- Tier 3 Alakazam used to be such a thing. When the raid system first got out, Alakazam solos were among one of the hardest things to do in the entire game. Not only it had incredibly high attack, it even has a high defense statnote , and even its best counters could get knocked out: Gengar was out in four confusionsnote , Tyranitar was out with a single Focus Blastnote and can OHKO Gengar or severely cripple Mewtwo with just one Shadow Ballnote . Thankfully, due to the double nerfs at late 2018 and much better counters such as Weavile and Giratina Origin being available, it's much easier than it is before.
- Tier 3 Flareon used to be incredibly difficult to solo, to the point that it became a Hopeless Boss Fight, because of its incredibly high defense combined with virtually no effective counters, as Golem and Vaporeon lack firepower. Thankfully, the availability of much stronger counters such as Waterfall!Gyarados, Kyogre, Smack Down!Tyranitar and Rhyperior, made the raid easier.
- Ninetales is another variant of Flareon, aside that it has more colorful coverage moves and its attack is lower, meaning that it doesn't give you a lot of charged move energy and it can instantly knock out nearly any counter using Solar Beam. This transforms it into a Hopeless Boss Fight. At the next time it is released, we have much more effective counters in addition to Rampardos and Palkia, although the latter does not have a water fast move. Beware though, as dodging Solar Beam will make the timer pretty close and will often activate server desyncs that might both destroy your Pokémon and heal the boss.
- Back during the Tier 4 existence, if you are trying to duo Metagross you are in for a surprise, because it is insanely hard, and even 6 maxed-out Moltres counters will defeat it in around less than 10 seconds left, assuming all of the Moltres are maxed-out and all players are Best Friends with each other.
- As far as lower Tiers go, Cloyster takes the cake. Cloyster is a Tier 2 raid boss, but its defense is so high that non-lv30+ Machamps and Raikous will fail to even tickle it. Thankfully due to the double nerf, it should be much easier than before if it returns, being lower in difficulty than Piloswine at Tier 3 according to online simulations.
- While Mega Raid Bosses are advertised as Tier 5 Raid bosses, they require a minimum of 6 players to beat and the Mega energy gained from each victory isn't enough to get the first Mega Evolution, which means having to beat the same Raid boss several times. It's even worse if you're unable to find other players to join the raid with you, as the Mega-Evolved Raid Bosses are absolutely brutal and can KO your Pokémon in a matter of seconds while only having a tiny sliver trimmed off their own health bar. Many consider them to be harder than fighting the Legendaries.
- Mega Charizard X is the worst of the bunch if it has Dragon Claw as its charged attack. Since Dragon Claw doesn't take much energy to charge, Mega Charizard X can and will use it multiple times against you in rapid succession. Since Mega Charizard X is part Dragon, Dragon Claw will get a boost in attack power, making it extremely lethal unless your lead Pokémon is tanky and can resist Dragon.
- The "neutral" female grunt. Neutral grunts use a mix of Shadow Pokémon that follow a certain theme rather than typing. While the male one is "starters" (they'll always have at least one member of the Kanto starters), the female one seems to be "strength": her lineup may contain PVP regulars such as Snorlax, Dragonite, Lapras, Poliwrath, Gardevoir or Gyarados, whose already high dangerousness level is increased with the Shadow bonus. This one can easily result in a Total Party Kill if you don't have something fast and strong enough, since they can easily knock out anything weak or even neutral to their typings. Needless to say, slow-charging Pokémon don't work. Have fun not knowing what to prepare for.
- If the male Normal-type grunt leads in with Teddiursa, watch out. What the Teddiursa lacks in power and durability it makes up for in sheer attack speed, resulting in it being capable of draining your first Pokémon's HP in only a few seconds only using its fast attack if you aren't prepared for it, even if your Pokémon resists the type of the move Teddiursa is using. Plus, it can sport the Fairy type attack Play Rough as its charged attack, making mincemeat of your Fighting types. Then, if you're really unlucky, you will have a Snorlax to go through after that. If the Snorlax in question has Lick as its fast attack, you shouldn't have much to worry about, but if it has the Psychic-type Zen Headbutt, there's a chance the battle may end with a Total Party Kill, as Fighting-type Pokémon are the usual choice to tackle on Normal grunts.
- Psychic-type Grunts can start with the tanky Wobbuffet which may have either Counter or Charm as its fast attack, which counter Dark type pokémon. It also gets STAB from Mirror Coat, its only charge move. Their lineups also may include one or two members of the Drowzee/Hypno line, which, in addition to their tankiness, were very sought out during the 2020 Kanto cup due to Hypno's varied moveset, which includes the powerful Ghost-type attack Shadow Ball and the Ice, Fire and Electric punches, which can nullify a lot of threats.
- Dark-type grunts have at least one member of the half-Poison Stunky line, which decimates fairies with Sludge Bomb (and Skuntank's Poison Jab) and neutralizes damage taken from Psychic (due to the Dark typing taking a quarter of damage from any Psychic attack) and Bug (due to its Poison typing doing the same) types while also dishing out quite a lot in return (with the Bite/Crunch combo) thanks to the Shadow bonus. The line even has the Fire type charged attack Flamethrower, for extra coverage. It's not uncommon to find Rocket grunts with three mons belonging to this line.
- Flying-type grunts can spawn with Skarmory, one of the high kings of the Great League. On top of its 10 resistances, access to the devastating fast attacks Steel Wing and Air Slash, and its bulkiness, it has the 20% shadow damage bonus turning it into a nightmare. And if you're really unlucky, at the end of the lineup, you may find a Dragonite, Crobat or Gyarados, which not only can tank Pokémon they're weak against but also decimate them in seconds if they spawn with the right (for them, of course) moveset.
- Arlo with Fury Cutter!Scyther was a nightmare in the early days. Take every annoying aspect of Scyther and Scizor packing the move and turn it Up to Eleven for a frustrating experience that also included either Magnezone, Crobat or Gyarados, the worst of the pack, who could shut down your Fire-types before reaching Scizor. Alternatives to Scizor weren't a cakewalk either: the Fire/Flying beast Charizard or the Dragon/Flying terror Dragonite. Have fun!
- Sierra usually has a Lapras on her team with water or ice based fast attacks that hit very fast. Thanks to Lapras being quite the tank with its defense and HP, you'll be chipping away at it while it steamrolls your team. On some occasions, Sierra will have two Lapras, or worse: Lapras as her first mon. Good luck taking down those shields!
- One of Cliff's early drops was Stantler, which could spawn with the Psychic-type attack Zen Headbutt nullifying its weakness to Fighting types.