Possessive nouns in article names

[Trainer-c]

Bulbapedia uses James's as the possessive form for all articles him. A pair of users have begun moving the articles on James's Pokémon saying that James' is the only correct possessive form. (You can see the discussion here.)

I checked the Manual of style and there is no mention of what standard we adhere to on matters such as this.

 

[Zhen Lin]

James's is correct, as prescribed by such authorities as the Chicago Manual of Style. Indeed, the very page the user cites says: (emphasis added)

• add 's to the singular form of the word (even if it ends in -s):
the owner's car

James's hat