Most decks have targets for him to eat up and even those few that don't still don't much like 2/3 fliers
Strong will grow quickly, but it needs some evasion to push damage through
How do you tell if a Pokmon card is shadowless
In between all of that, you have access to attacking with Radiant Greninja [Astral Radiance] to snipe some of your opponents Pokemon, and you can also swing for some easy damage with Dragonite V [Evolving Skies]
While Crispin is a card that is useful in decks that use multiple types of energy, some decks can't make use of it because they only have access to one energy type
It can make a small army of flyers to evade Moat (or block opposing flyers), and it if sticks around until your next upkeep essentially renders an opposing Swords to Plowshares or Disenchant irrelevant, as it will have had time to separate in to four smaller threats at the beginning of your upkeep