There's no flag to say if the pkmn is a ultra beast

[leobetosouza]

Ultra beasts are a special kind of Pokémon debuted in Pokémon Sun and Moon. More info: https://bulbapedia.bulbagarden.net/wiki/Ultra_Beast

For example, Naganadel.
Pokémon: https://pokeapi.co/api/v2/pokemon/804/
Specie: https://pokeapi.co/api/v2/pokemon-species/804/
Form: https://pokeapi.co/api/v2/pokemon-form/804/

Neither as a attribute that indicates it is a ultra beast, like is_baby (in the specie endpoint) or is_mega (in the form endpoint)... is_ultra_beast isn't a bad one.

Currently the only know way to say if the pokémon is a ultra beast is checking the ability Beast Boost. But, I think it is not the best way to do it. I think the APIs can be more explicit regarding this. And, I think it is not future proof, since someday Game Freak can change the dependency of Beast Boost.

[phalt]

This is a good point. It shouldn't be hard to add this attribute to data currently. Feel free to make a pull request with changes and we can help review it and merge it.

[Naramsim]

Adding a new flag is_beast would be easy but not maintainable. We rely on the data format decided by Veekun. They currently don't have any flag for identifying a beast pokemon. @nairraghav added successfully it to the CSV pokemon_species file but I asked him to remove it since this would break future updates from Veekun.

You could suggest over here to add the new property.