Out of any of these i'd say the most impactful would either be partygoers or Thing on Level 7. Removing The Thing on Level 7 would make Level 7 safe or outright habitable, and removing partygoers would not only remove one of the most OP universal entities but also make level fun a habitable level that's genuinely full of cake and parties
Clumps aint shit they're like even stupider hounds that are loud and noticeable. You definitely wouldn't win a fight against one but avoiding them would rarely be an issue.