I honestly don't know if this post would be leaning too far into competitive play for the purpose of an Orange Islands thread, but I wasn't sure where else to complain about this. So by this point I'm sure you all know about the Ghost and Dragon-Types.
(I mean, if you're enough of a Pokémon fan to even want to be on this site, I'd hope you know about all of the Types by this point.) These are the only two Types in the game whose attacks can inflict super-effective (2x) damage onto Pokémon of their own Type. The idea that any Pokémon type is able to do this is something I have a pretty big problem with from a game balance perspective because of how Pokémon handles the Speed stat and turn priority. To represent why I have an issue with this, let's take a look at two Hoenn Dragon-Types with very similar designs for the purpose of Pokémon battles:
With most Types that may attempt to win a mirror match against a different species of the same type, there tends to be a lot of factors that might determine which Pokémon comes out on top. A Water-Type with access to Thunderbolt, for example, would be more likely to win against an opposing Water-Type that doesn't have any Electric or Grass-Type moves. Admittedly, there are still dual-typed Pokémon to take into consideration here, but either way most of these Pokémon generally won't run into this issue since those Types of attacks are either neutral to or resisted by their own Types. Since a player's best checks to a Ghost or Dragon-Type Pokémon might often be their own Ghost or Dragon-Type Pokémon's STAB attacks respectively, however, this dynamic suddenly becomes warped. More specifically, the matchup between these Pokémon will often become warped in favor of the faster Pokémon regardless of other qualities such as held items, Abilities, et cetera. Take a look at Salamence and Rayquaza again. Someone who's just discovering a Pokémon as strong as Rayquaza exists for the very first time would be understanding to think it could win a matchup versus a Salamence. In practice, the Salamence, assuming both Pokémon have the same amount of Speed IVs and EVs, would be much more likely to win since it's slightly faster than Rayquaza and still has the offensive stats to prey on Rayquaza's lower defenses by Legendary standards.
Especially with how many strong Ghost-Types exist in recent generations, I don't think it's smart for this kind of thing to be a factor when these types are supposed to be the ones that can check themselves as a way of keeping these Pokémon from being overpowered. Even in single player, we've seen this interaction be a major factor in pushing certain Pokémon like Cynthia's Garchomp, Morty's Gengar (mainly in HGSS because of special Ghost moves being a thing, but still), Shauntal's Chandelure, and Dragon Dance Haxorus used by either the player or an NPC over the edge by further limiting how many viable options casual and experienced players may have to deal with those threats. In fact, I'm convinced Garchomp was specifically designed to do this- its base Speed outspeeds even Palkia, not even the part-Steel-Type Dialga is safe because of its Ground STAB, and the only other Pokémon in any of the Sinnoh games with a good type matchup that could also match its pace would be Weavile and... your own Garchomp. All other options lose to at least one of either Brick Break, Flamethrower, or Poison Jab (BDSP).
