Why play Edison
While a few of them are gimmicky, overall it's proven to be a pretty solid archetype in its own right, even in today's Power Creep, with a few Synchrons being staples of many Synchro heavy decks, especially Junk Synchron
The flavor text is also stressing that the silver-bordered creature destroyed was a Donkey
A turn 1 Eviolite, however, forces Yanmega to attack at least four times to KO a Mewtwo, and other Pokmon, namely Reshiram, does this more efficiently
This card sees play in nearly every green deck, even decks where green is just a splash color, from Galea, Kindler of Hope decks to Vorinclex, Monstrous Raider decks and Wulfgar of Icewind Dale decks
The last thing I'd like to touch on for strengths is the fact that Chaos Warrior doesn't get respected as much as it should or could (though this perception is slowly changing)