Like a Dragon: Infinite Wealth

Easy one, this. As in the previous game, you'll collect enemies in a Sujidex. Keep getting into fights, and, eventually over time you'll register 200 Sujimon to your Sujidex. By chapter seven, I'd reached more than 100, so by the time you've finished the game and tackled some of Infinite Wealth's dungeons, this should be yours. Note also that new enemy types are introduced at the start of Chapter 9. There are 317 Sujimon in total, spread across both Japan and Hawaii.