Just commenting on my own levels here, if you were to remove any it should probably be light switch. As amusing as I find the level, the more players you add the less well it works. That would leave 3 (I think) of my levels included, which is probably more reasonable if anyone has a problem with 4 of them being featured.

If you want to lower that to two levels, I would recommend keeping island level with islands and emnsef, since those are the two actually designed for larger player counts.