First topic message reminder :
So, I'm sure anyone who doesn't live under the rock is aware that you can only reach the water dungeons on the site by having a Water-type character or having a Water-type ferry your character there (at which point you probably wouldn't be able to do much because the character can't breathe under water or hold their breath long enough.) This system seems simple enough, right? No changes required?
WRONG!
Logically, whether or not one can enter these dungeons should not be based off their type, but off whether or not they're capable of that level of swimming. This can easily be determined by whether or not the character is capable of learning both Surf and Dive. Surf shows long-distance swimming capabilities and Dive shows the capability to remain under water for extended periods of time. Now, I know what you may be thinking: "But, but, that's the exact same thing as Water-types, they can all swim and dive!" Well, wrong again!
Some Water-types actually can't learn the HMs Surf and/or Dive. On top of that, there are some non-Water-types that CAN learn both, and some that can learn Dive and could easily just fly to the area before diving in as opposed to surfing. Don't believe me? Check for yourself. I'll use Dragonite as my example because Dragonite can fly and learn Dive. Logically, it should be able to enter water dungeons because it is clearly perfectly capable of doing so. Meanwhile, something like Lotad should not be able to really get anywhere because it's stuck floating on the surface, as shown by its inability to learn Dive until it evolves.
Next, you probably want to argue that Surf/Fly and Dive aren't good indicators of whether or not one is capable of accomplishing such a feat, because they're HMs, which means they TEACH the Pokemon how to do this when it previously couldn't. Well, YOU'RE REALLY GOOD AT BEING WRONG THEN! Surf merely teaches a Pokemon already capable of proper swimming how to properly ferry someone along with them, and how to summon and control waves for some reason. Fly teaches a Pokemon how to fly extremely fast for extremely long periods of time, and thus make it capable of inflicting noteworthy damage in a battle. Dive teaches a Pokemon already capable of diving how to properly carry someone down under water with them and it apparently teaches them how to dive into solid ground or something but lets just pretend that last part doesn't exist because it makes literally no sense.
Also, I don't think Pokemon should be capable of "ferrying" others to water dungeons. Now, here you may want to argue "But if they're capable of surfing, that means they're capable of ferrying someone across water according to you!" Well, for once, you're not wrong, so congratulations! However, consider this; what exactly is a Pokemon incapable of extended diving supposed to do once they are ferried to a water dungeon? Sit on the surface? Yes, they can logically be brought there, but they can't really do anything once they get there. WHY would you want to do that? Why? The character technically can't really even get to the actual dungeon, as all of the water-based dungeons are UNDER the water. What is the Water-type supposed to do, give your character mouth to mouth constantly to give them oxygen? If they're holding their breath, they have little-to-none to spare, and if they're breathing through gills of any kind (be it internal or external,) they do not have pure oxygen to give to you and would drown you trying to do the opposite.
Airborne/floating places, on the other hand, SHOULD allow for "air-ferrying" of sorts, because one could logically walk around up there just fine once brought to the area. Yet I don't see any mention of it being allowed for those capable of reaching the floating areas to carry others up with them, so I feel that should be addressed. You can drag someone under water with you without them drowning, but you can't fly them up to a place that floats? Also, there should probably be a weight limit on who can carry who, because I'm just not seeing a a Zubat OR a Magikarp carrying a Snorlax anywhere.
TL;DR, entry to water dungeons should be based off whether or not the Pokemon is capable of learning Surf/Fly and Dive. Also, Pokemon should be allowed to be carried to floating areas if they can't fly, and Pokemon should not be allowed to be ferried to water dungeons, or at the very least, what one can do once ferried to a water dungeon should be extremely limited if they can't learn Dive.
Side note, don't take my mock-hostility seriously, anyone who knows me should know I like to joke. 3