There are a few options here:
1. Do nothing: https://soundcloud.com/megaflare0/bibim … ght-teaser (1:30ish)
This works fine when you have a full sounding song even without the pulse channels. It's pretty hard to know when this works and when it doesn't, so just go with your gut and when in doubt try to add something and then decide if it works. You're going to want to do this when your sound design is the main focus of what you're trying to do. Basically, if your wav channel sounds rad on its own don't think that you need to add something.
2. Percussion: https://soundcloud.com/monodeer/derp (1:08ish)
Don't be fooled into thinking the pulse channel can only be melodic, when you use V commands with really high values or play around with the transpose function in tables you can get some interesting noisy drumish sounds. Monodeer uses what I assume is a VFF command to get a cymbal sound in a channel where those don't usually belong.
3. Back your wav channel: https://soundcloud.com/possibly-a-fake- … -last-post (0:44) (shameless self promotion)
Your wav channel can only go so far on its own, sometimes it needs a little help from its friends. Both pulse channels are backing the wav channel in this song at some points, and although it still sounds like a wav bass it has extra meat thrown in from those extra oscillators. Doing this keeps you from "wasting" channels while keeping your song sounding full and yet simple. My usual pulse sub is a 50% pulse at about volume 4 or 5, "sidechaining" under the wav kick. The goal here is not to give your bassline a bassline, it's to get your pulse channels to melt into the wav channel and make it sound like one instrument.
4. Just do other stuff: https://soundcloud.com/boaconstructorbe … ow-on-tbbr (1:50)
Your pulse channels can do things while your wav channel takes center stage, it just takes careful volume control and sound design. I don't really know how to do this all that well but I'm sure if you do enough listening around and trying things you can work something out.
