Chikorita is the Grass-type starter Pokemon of the Johto region, and as of Pokemon Scarlet & Violet, you can catch one of your own in Gen 9. Like every other pre-Gen 9 starter Pokemon, you'll need to contribute some Blueberry Points (BP) to expand one of the Biomes in Terarium. While Terarium is exclusive to the Indigo Disk DLC, you can get Chikorita and its evolutions via other methods such as trading. Even if you don't intend on using Chikorita/Bayleef/Meganium in battle, you'll need to have each of them in order to complete Indigo Disk's Blueberry Pokedex.