<!-- Thanks for contributing to the PokéAPI project. To make sure we're effective, please check the following: - Make sure your issue hasn't already been submitted on the issues tab. (It has search functionality!) - If your issue is one of outdated API data, please note that we get our data from [veekun](https://github.com/veekun/pokedex/). If they are not up to date either, please look for or create an issue there. Otherwise, feel free to create an issue here. - Provide a clear description of the issue. - Provide a clear description of the steps to reproduce. - Provide a clear description of the expected behavior. Thank you! --> Steps to Reproduce: 1. [See document](https://pokeapi.co/docs/v2#evolution-chains) to ensure that `EvolutionChain.region` and `EvoluionChain.base_form` is defined. 2. Access https://pokeapi.co/api/v2/evolution-chain/24/ 3. They actually does not exist. Instead of these, it have `region_id` and `base_form_id`.