From my personal experience, I just recently got a "hi-fin spotted pleco" it's probably a colloquial name rather than it's real name, but I caught him sucking on my senegalus's side a couple weeks ago, I haven't seen it latch on since then so I'm not sure if it will continue, but make sure your pleco isn't doing it too regularly. He isn't more than 2.5" so it isn't just large plecos that will eat slime coats. Sorry no pics, it didn't last long and I didn't even think of taking one.
There are species that won't feed on slime coats, but each fish has it's own personality so you may have to find a species that works for you.
One more thing, it isn't just the pleco you have to take into consideration. The fish you're mixing with them also matter, fish that stay still will generally be more likely to be fed on.