I really like 'A New Alliance'. In this fanfic, Momo and Lemillion team up to create a new training regime for the students at UA. It delves into their different quirks and how they can complement each other in a training environment. There are some really cool action scenes as they test out their new training ideas on each other.
One popular trope is the 'Mentor - Mentee' relationship. Sometimes, Lemillion is written as a mentor to Momo, teaching her how to be more confident in using her quirk in combat situations. Another is the 'Partnership' trope, where they team up for various missions and grow closer as friends and comrades.
The main differences might be in the character designs or the plotlines. Sometimes, they could tweak the backstory or add new elements to make it more engaging.
Common features include unique hair colors like purple or pink, and elaborate hairstyles with braids or curls. Also, the hair often moves smoothly and realistically in action scenes.