In Underswap, Undyne is very similar to Undertale Alphys, as she likes anime, science and is very nerdy. She is also shipped with Underswap Alphys. She is close with Alphys, Toriel and Papyrus (maybe).
Undyne wears a lab coat a pair of boots and glasses. Undyne also has red hair and a pair of boots
Undyne's personality, roles, are still the same, the difference is that she is swapped with Alphys, she is more nerdy than Alphys but still loves to say punk.
Undyne and Alphys are madly in love just like in Undertale.