Collect all Folks for Ellen and Keats.
Increase ID's Karma:
When you capture certain ID's, to increase their power they'll require you to capture more of their type of ID as is the case with the starting Pouke Id, and many more. Once you capture these ID's, simply exit and return to the spot and you can fight and capture the ID's again, quickly powering up your ID before you even use the ID fully.
If you see an item that you require to increase the Karma level for an Id, then you can leave the areas and return. This will respawn the Items, which you can take, leave and return again till your hearts content.