Transformations/Stages are allowed, for example Ruin Dust or Emotionless Ink

Alternate versions are allowed, like Fellswap and GG!Fell

No prejudice is held, it’s a fight to the death.

If someone will lose a fight but can’t die, i.e Nightmare only killable from positivity, it also counts.

No DT/Save hacks

Duos/Trios/Groups are allowed in reason (I.e BTT)

I reserve the right to not allow a suggestion that obviously cannot win or is a joke.

No repeats.

Day 1 - Sans

Day 2 - Rejuvenation Papyrus

Day 3 - Undyne the Undying

Day 4 - LV 19 Clover

Day 5 - Underswap Papyrus

Day 6 - Canon Horror!Sans

Day 7 - Bullet Train LB! Phase 2

Day 8 - LB Phase 2 (The Slaughter Continues)

Day 9 - LB Phase 3 (An Enigmatic Encounter)

Day 10 - SIXBONES

Day 11 - Cereb (Battle With a Think Tank)

Day 12 - Canon Fell!Sans

Day 13 - Swapfell Papyrus

Day 14 - Dusttale:Setback Ruin Dust (LV 3)

Day 15 - Ruin SP!Dust

Day 16 - Preboot SS!Chara

Day 17 - Revenge Act 3 Papyrus (No Gaster/Souls)

Day 18 - Devilovania SS!Chara

Day 19 - Pacifist/Neutral Undershuffle Sans

Day 20 - Ruins Outerdust LV 4

Day 21 - Undertoad Mario

Day 22 - Ruins Felldust (LV 4)

Day 23 - Hardtale Sans

Day 24 - Dustbelief Sans Encounter (LV 5)

Day 25 - Underfell:Stories Of The Sea

Day 25 of what is the WEAKEST AU character that can beat this character? Underfell Stories of the Sea Sans was beaten by Hardtale Sans (buggedbeatle998's take)