Bug Fables: The Everlasting Sapling

This achievement can only be obtained after starting chapter 4 as you need an ability you unlock in Chapter 3, and a character to be at a certain spot, which only happens during the events of Chapter 4.

After completing chapter 3, head back to the Golden Path. In the lower areas, there should be thorns. With Leif's overworld ability (the bubble), you can traverse the areas. In one area, there will be a cave with many Chompers in it. At the end will be a Mother Chomper, which will be a boss fight. It's actually a relatively challenging boss-fight if you go into immediately after chapter 3, and took me multiple tries.

You must also talk to the assistant of the old lady bee (Professor Honeycomb) that upgraded your Beemerang during Chapter 2 (the assistant's name is Hawk), as part of the story in Chapter 4, in the Lost Sands. After doing so, he'll give you a quest item, and return to the Bee Kingdom.

EDIT: You must also acquire the Tardigrade Shield medal from the Lost Sands in order to make Hawk return to the lab. The medal can be found one room to the right of the Bugaria Outskirts Entrance, and then one room north of that. Then, you must solve a small puzzle in order to access the top of the arch where the medal is.

After defeating the boss, you should get a Chomper Seed. After talking to Hawk as part of chapter 4, and obtaining the medal, take this to the Bee Kingdom, to the workshop with the crooked glasses above the entrance. Talk to the Prof. Honeycomb, and eventually she will ask for your Chomper Seed. Give it to her, a short cutscene should play, and then will produce a baby Chomper. After the cutscene is over, the achievement should pop, and you'll have a new friend that you can take into fights with you!

Here's a video that shows where the Chomper Cave is in the Golden Path, by Youtuber sk vi Responsible: