How strong a character is base wise in terms of power/damage is determined by when they were originally released, so the the newer the character are release wise the better they are.
That said, a character can become good again through Refreshes, however the oldest characters like Mickey, Goofy, Woody and Ralph probably need a proper Refresh and not just a Stat Refresh.
Refreshes are what can make old characters useable again, proper Refreshes are where the skillsets are changed like adding new effects, extending duration and of course increased damage potential.
Stat Refreshes are just increases in the stats like more HP and more damage power for example, however may not necessarily make them be able to compete with the newest characters, however Stat Refreshes do in general still make characters more usable like from going from a C rank to A rank tier list wise, even if not S rank as in becoming meta.
From what Loutre/Nugget has said proper Refreshes should more so come back soon, so characters like Mickey, Goofy and Woody could get a proper Refresh :-). Unfortunately Ralph is a starter character, so he isn’t likely to get a Refresh from what we understand.
Hope this explanation help you some MisterDavid :-).
(Hope you Loutre/Nugget don’t mind me explaining, but yeah like to help if I can).