I feel like the thing about Pokémon’s type chart is that every Type is designed to have some form of use and that even the worst Types in the game can thrive in the right situation. Trying to decide if any Types are over or underpowered isn’t a matter of looking at which Types are strictly the strongest and against what, but rather it’s a complex puzzle that dives into the core mechanics of the game. Which Types are good for a win condition? Which types are good for a defensive pivot? How much opportunity cost am I spending by picking this Type of Pokémon over another? Things like that. Sometimes, you’ll have situations where added mechanics seemingly “break” already existing Types, too- see how Power caused some controversy way back in the day in Gen 2 with the Legendary Electrics in particular because that design archetype wasn’t designed around the idea of universal type coverage.
Every time there’s been Types Game Freak wants to tone down, there’s been some common trends between those Types. In their eyes, a “broken Type” needs a handful of things, and preferably a combination of them. It needs a deep roster of strong Pokémon of that Type, it needs a deep roster of good moves or at the very least one move so good that it helps carry the entire Type (see Psychic in Gen 1 and Close Combat in Gens 4-5), and it needs good unweighted and weighted matchups both offensively and defensively. When new generations are created, however, we see a scenario where already strong Types tend to get even stronger… at the cost of their bad matchups also getting the same treatment. Power creep is a universal phenomenon in this sense, and for that reason I don’t there’s any one Type in the game right now that’s overly dominant or completely ruinous, since even the strongest Pokémon tend to have equally viable answers because of all of the power creep.
Instead of broken individual Types, what we’ve seen more and more of over time is a shift towards overpowered Pokémon who are as strong as they are for reasons other than their typing. Now, it stands to reason that several Ubers are strong because they can use their STABs or whatever, but something like a Mega Kangaskhan pre-nerf or a Prankster Thundurus, to say nothing of all the threats running around in Gen 9, is probably going to be strong no matter what Type(s) it is. Conversely, if a Pokémon’s base stats, movepool, and Abilities aren’t very useful, it’s going to be way harder to make use of whatever typing that Pokémon is given. This is an extreme example, but you could have a Steel/Fairy Pokémon with a deep movepool, incredible base stats, and something like Truant as its only Ability and the Pokémon would still probably be unviable.
Refer back to what I said about the Legendary Electrics in Gen 2, however. No tiering action against them or against Hidden Power currently exists at this time, but when newer mechanics are introduced that massively warp the metagame in favor of certain Types like this, specifically those features the Type chart wasn’t designed for, that’s the kind of thing that breaks a Type in the traditional sense. Rock-Types tend to be slow? Say hello to Speed boosting strategies and both Dragon Dance Tyranitar and Choice Band Aerodactyl in Gen 3 who bypass many of the normal issues Rock-Types are known for. Most Dragons have higher physical Attack in the older generations? Say hello to the physical-special split. Fairies being resisted by the three Types with the most resistances? Slap a Ground Tera on that bad boy and watch as your problems disappear.
Edit to prevent double posting: This whole concept of “later introduced mechanics can break older strategies” is arguably the entire reason Baton Pass has been so controversial for so long, By nature, being able to do things like pass stat boosts or make use of “slow pivoting” (as opposed to the immediacy of just switching out normally) changes how the game is to be approached. That begs the question, though- is every newly developed strategy like this “broken” by definition, if you’re speaking as strictly as possible? And wouldn’t that mean Gen 1 is technically the only generation with nothing (besides Mewtwo and Mew I suppose) “broken” about it at all?
