Every character is planned to have a niche. Whereas Poppi is designed to be a massive threat. Others like Sammy Or Nile will have less offensive niches. Sammy's role is to tease, and toy with the player. When discussing this with the team, and looking back at the player feedback we decided we can showcase her character traits with different gameplay.
Now you talk about assist creatures. Misty the shark will have a massive punisher for noob players. She will be a great assistant to players who learn the systems, and play the game well.