From PinataIsland.info, the Viva Piñata wiki
Opening at level 7 in the village, Gretchen Fetchem is a hunter. She'll happily track down and capture any pinata you have already had in your garden. This is very useful on a lot of higher level pinata, where taming another one would take too long.
Gretchen offers three services:
- Express catches the pinata relatively quickly, but costs double that of standard.
- Standard catches the pinata ridiculously slowly, but for a lower price.
- Retrieve Dragonache. This option appears once you have sent a Dragonache away. Gretchen will fetch it free of charge.
Once Gretchen has caught the requested pinata, you will receive an alert, and an option to place the pinata will appear. You can also release the pinata if you told her to catch the wrong one by pressing on this option.
Also worth noting is that Gretchen- after a while- will release your pinata if you leave them with her for too long.