When it comes to a character specifically choosing to hold back then Superman takes the cake. When it comes to characters being "held back" by the plot and writers..I'd say Flash wins that.
It gives you an idea of how broken certain versions of Flash are since the current version really doesn't even compare to Wally.
__________________ Chicken Boo, what's the matter with you? You don't act like the other chickens do. You wear a disguise to look like human guys, but you're not a man you're a Chicken Boo.
Flash at times probably fights closer to his potential then Superman does though. Probably because Superman has so many powers while Flash doesn't.
__________________ Chicken Boo, what's the matter with you? You don't act like the other chickens do. You wear a disguise to look like human guys, but you're not a man you're a Chicken Boo.