Enough about unused type combinations, what are some type combos that you DON'T want to see return in the next generation?

We've got enough Fire/Ghosts and Grass/Ghosts at this point, we can give them a break.

Also Water/Ground. I know we didn't get any new ones in Gen 9 but we've got enough already so we can just keep rotating the ones we have in/out of circulation for another one or two Gens before needing another.