[Misc] Sinistea and Poltchageist line alt forms now available

[Madmadness65]

What are the changes the user will see?

Antique form Sinistea & Polteageist, Artisan form Poltchageist, and Masterpiece form Sinistcha can now be encountered in the wild. As their form differences are only visual (and a small difference at best), there isn't a way to tell until you catch one.

Why am I making these changes?

It is a forgotten form difference Pokémon and it makes them available in this manner. You could already get the alternate forms via evolution item, however.

What are the changes from a developer perspective?

Entries added for the Sinistea and Poltchageist evolution families in the getSpeciesFormIndex.

Screenshots/Videos

How to test the changes?

Encounter any of the Sinistea or Poltchageist lines, either naturally or via species override. The alternate forms will have a chance to appear.

Checklist

• I'm using beta as my base branch
• There is no overlap with another PR?
• The PR is self-contained and cannot be split into smaller PRs?
• Have I provided a clear explanation of the changes?
• Have I tested the changes manually?
• Are all unit tests still passing? (npm run test)
  • [N/A] Have I created new automated tests (npm run create-test) or updated existing tests related to the PR's changes?
• Have I provided screenshots/videos of the changes (if applicable)?
  • [N/A] Have I made sure that any UI change works for both UI themes (default and legacy)?

Are there any localization additions or changes? If so:

• [N/A] Has a locales PR been created on the locales repo?
  • [N/A] If so, please leave a link to it here:
• [N/A] Has the translation team been contacted for proofreading/translation?

[DayKev]

There's zero difference in Pokerogue with those forms though, not even a minor visual difference because we don't use 3D models and the difference is on the underside. They might as well not even be in the game.

[Snailman11]

Have you checked the spawning for Poltchageist and Sinistcha?

[Fontbane]

Shouldn't they be 1 in 100 rather than 1 in 2?