Lucina outranges Dr. Mario and Doc's mobility is slow and Lucina can edgeguard his recovery easily, however Dr. Mario does have a projectile to use against Lucina, and unlike Marth Lucina does not have to space with tippers to kill or be safe on shield as Dr. Mario's recovery is one of the worst in the game and Doc struggles against Marthcina's range. My vote - Dr. Mario 3 / Marth 7
Lucina wins this MU like Marth.
Lucina outranges Dr. Mario and Doc's mobility is slow and Lucina can edgeguard his recovery easily, however Dr. Mario does have a projectile to use against Lucina, and unlike Marth Lucina does not have to space with tippers to kill or be safe on shield as Dr. Mario's recovery is one of the worst in the game and Doc struggles against Marthcina's range.
My vote - Dr. Mario 3 / Marth 7