>>36774548Bug. Unremarkable defensively, and absolute dogshit offensively, to the point special buggos like volc sometimes don't even run bug STAB, and physical buggos only like it for u-turn, or also don't run it at all if they can avoid it, like mega pinsir. On top of its matchup, it doesn't have great set up moves other than QD (small distribution), support moves like sticky web (small distribution), or strong/useful attacks other than megahorn or u-turn (distributed and used mostly by things that aren't even bugs).
Grass is bad offensively but it has some key resistances and leech seed is annoying. Rock and ice are too good offensively to be called the worst types. Poison is another likely candidate tho, although I feel it fares better than bug if anything because it's decent defensively.