Ok. If I were designing a Smash game, then that’s what I would do.
The balancing of the evolution meter would be astronomically difficult. Just in terms of how it fills up even. Dealing damage fills it and taking it decreases it. I guess half full let’s you go Greymon, full full gets you WarGreymon. And if you take enough damage to set your meter below certain threshholds you revert to a previous form. And if you go below 0 you become Koromon for a few seconds and he only has like, one or two special moves.
He just feels.... redundant.