Soft plastic leeches will work for largemouth bass. You can fish them on a variety of rigs, but some of the more common rigs are a jighead, drop shot rig, shaky head jig and a weightless rig.
Best Rigs for Soft Plastic Leeches
Drop Shot Rig
The drop shot rig is the best rig for giving a soft plastic leech the most action. You can fish it shallow or deep and have a lot of success with this rig.
A simple jighead is how most people rig a soft plastic leech. If you are hopping it along the bottom or vertically jigging it for suspended fish, you have a good chance to catch some largemouth bass. Just make sure to give it plenty of action.