basically its kinda similar to regular undertale but the 10th anniversary scenes are there and theres new characters sans is replaced by lenny the lizard, alphy's brother with knowledge of the spacetime continuum. you meet him in snowdin (he and his brother prefer the cold) and appears occasionally throughout the game and you have the mandatory no mercy fight papyrus is replaced by francis, lenny's little brother who tries to hoard tons of stuff from the human world. like papyrus, he wants to be a royal guard member and idolizes the mighty gerson boom. he fights you but then realizes that being a royal guard member isnt all its cut out to be undyne is replaced by gerson. you know him you love him. unlike undyne he doesnt try to defeat you, until he challenges you at the cave where you fought undyne. he came out of retirement after undyne got fired from the position of royal guard chief undyne is in gerson's shop btw mad dummy is already mad mew mew but instead of the switch soul its a pink and yellow soul because mew mew is pink and yellow i think alphys is replaced by w.d gaster, the royal scientist who seems calm, but is secretly very anxious. he wears a mask to hide his face mettaton is replaced by mr ant tenna, who isn't a darkner, but a ghost in a body that looks like tennas beta design. like deltarune hes animated in mocap but in battle hes animated in a manga style. he has a neo form instead of ex tenna doesnt appear in no mercy but instead of mtt neo theres an empty neo body that fights you the enemies in hotland are the beta ones that were mentioned on stream the core is a different layout because it can be changed regular gaster is replaced with alphys the old scientist
c2a characters left to right asgore, gerson, toriel, lenny, gaster, and francis
