Kind of a Morton’s Fork situation there- either you are constantly swapping, which would get really old really quickly, or the character would be grossly overpowered.
Which would be ironically fitting, given that Mare-Do-Well’s entire purpose was to be overpowered compared to Rainbow Dash.
Were this to be an actual Mare do Well game, would you have to constantly swap to someone else to use flight/pinkie sense/magic/strength? Or would a single character have it all?