Aggrons role in the mainline games is typically as a powerful ally, often serving as a challenging opponent in gyms and the Pokmon League, particularly under the ownership of trainers like Steven Stone, the Champion of the Hoenn region
Adding other colors makes decks stronger because it accounts for the weaknesses of each color and diversifies the tools at your disposal
Its rare for there to be more steps in the evolution chain than this
Modern is has a reasonably high amount of graveyard use right now, so tacking on the ability to exile a graveyard on to a spell that has two other modes is quite powerful, as it allows you graveyard interaction when you need it, but youre not stuck with it when you dont
This is thanks to the leaked Hatsune Miku deck, which will, naturally , want more Miku