Cetaceal how do I get that?

[Arcaneumkiller]

Hello, looking at the Pathfinder wiki I came upon one of the coolest(in my opinion) Outsider creature I seen in the entire bestiary of Pathfinder. The Cetaceal

https://pathfinderwiki.com/wiki/Cetaceal

Basically a Neutral Good Celetial Creature (or Agathion) that dwells in Nirvana (the Neutral Good Plane). An aquatic humanoid female with an Orca tail. Armed with a short spear.

1- Anyways, does that creature currently exist in 2nd Edition?

I checked on the Archive of Nethys, in the Agathion family creature but it is not listed.

2- If not, what is your position about the lore of 1st Edition being still valid if not retcon by anything from 2nd Edition?

3- Does that fall into Homebrew territory or is that like a official position from the Paizo that until written otherwise we are ok to assume anything that hasn't been revised from 1st still hold true?

4- Assuming the creature exist but simply does not have a stats, what would be the closest thing to it, I was thinking maybe I could reskin an existing creature?

** If possible one creature that that I would have the ability to polymorph into **

5- (My attempt) Alternatively, would you allow the following at your table;

Celetial Form Assimar Heritage Feat LV 17
Presquisite: Angelkin, Emberkin, Idyllkin, Lawbringer, Musetouched or Plumekith and able to cast angel form with a spell slot
Frequency: Once per day

You've discovered how to transform into the form of your Celestial ancestor. Once per day, you can cast 8th-level angel form as an innate divine spell, transforming into the following depending on your lineage;

Angelkin - Any Celestial with the Angel trait
Emberkin - You transform into a Peri
Idyllkin - Any Celestial with the Agathion trait
Lawbringer - Any Celestial with the Archon trait
Musetouched - Any Celestial with the Azatas trait
Plumekith - You transform into a Garuda

Obviously, each would have the same core stats and each form would have varying weapons and traits choise based on the different creature with those traits.

[Perpdepog]

1. No, it doesn't. That just means it hasn't been written up though, not that it doesn't exist in the setting at all.
2-3. Pretty much what you said. Anything that isn't expressly revised by Paizo holds true as regards canon. Sometimes that can be a bit nebulous to discover, sometimes bits of their canon no longer fit their vision for the game and are removed outside of rather than inside the product line, but yeah. Your assumption is correct.
4. Personally I would try to recreate the creature with PF2E's charts, though I recognize that isn't super helpful for ease of play since you'd have to pick which parts of the creature's statblock are the most important and use those. 2E has more constraints on monsters than 1E did, lots of abilities were toned down between editions, particularly regarding defenses and capable martial monsters also having good spellcasting.
5. If your goal is to make battleforms then sure, go for it I say. I'd be much more suspicious if the ability straight turned someone into that monster or gave them the monster's whole chassis; monsters have abilities that can be considerably more efficient than what PCs can do in order to bridge the gap between the PCs class features and teamwork and so on.