I disagree. I and many other people like to be able to reset the damage without having to manually go to the reset button, which also resets the positions of the characters.
An idea that I always thought should be implemented into the smash games is more control settings for the training AI.
Having options like 'always shielding' and 'always crouching' would be a nice way to test things like crouch cancelling and what moves are good for shield pressure, without needing another player.
Options like 'always DI up', 'always DI down', ect. could possibly be added too.