PS. I'm telling this without playing it actually. I badly want to try it and post again critically praising the hack.
And sorry - when I start typing, I go on for[I]ever[I]. So sorry...
Hey, thanks for posting. You know, I've made those Pokémon you mention quite stronger, in this game there are not Pokémon that are horribly outclassed by others.
The progress is slow because thinking of movesets for more than 600 Pokémon is slow, but I am still working on this (now it's hard because I have university exams, but I'll work on this in summer a lot, I'll even try finishing it).
About Castform, it has 80 in everything, except for Speed (100) and Sp. Attack (110). It has improved quite a bit.
The Marill line now has usable Special Attack, but Azumarill's selling point is Huge Power, and it is great as it is, well, now, it's Attack is even higher, it has 60 base Attack, which means that with Huge Power, its attacks hurt a lot.
About Johto Pokémon, Snubbull is now quite good, I advise you to train it because it appears in the first Route. Girafarig with Adaptability packs a punch too. Dunsparce and Delibird are far from useless, Mantine has even better Sp. Defense, and nice Sp. Attack as well, Shuckle has a nice HP stat to back up its amazing Defenses, as a Rock/Grass Pokémon with Head Rock, Sudowoodo's Wood Hammer is amazing. Noctowl is now Psychic/Flying, and it's Special Attack and Speed are quite improved. IDK, I've improved many Pokémon, not just Johto ones, but you can see that Johto Pokémon are good.
And about Splash and Banette, I won't be changing sprites, sorry... And Splash will stay as it is now.
You should try the game and see if you like it. I really need people to play it because I want to know people's opinions.