Ultimately, it wont be worth doing so if your deck doesnt have some manner of sacrifice theme and ways to use the extra mana, but Magic has been incredibly long on both of those things for years now, and sacrifice decks show up in more and more Cubes all the time
This means adding Mew ex to the deck makes your Dialga ex more consistent as well, since no Energy is being wasted
The deck's ability to generate value, ramp, and draw cards makes it consistent and explosive
A one-drop with the potential to grow continuously throughout the game is no joke, as Heartfire Hero has taught us
You must have a Benched Pokmon to retreat to
Fans have grouped these winning strategies into six main 'archetypes', based not on which cards they include, but on how they set out to win games