Remember, rules make the game fun, and knowing which cards are in the pool impacts your strategy
If the creature you control is an illegal target as the ability tries to resolve, you won't put a +1/+1 counter on it
The Pokmon Trading Card Game was mostly unchanged during the entire Wizards of the Coast Era (1996-2002), but when the game changed hands and Nintendo began to develop cards along with the Pokmon Trading Card Game Company, they made a mechanical change to the game that would alter the way it was played forever
Thats because on digital platforms, it goes by a different name: The Terminus of Return
This means I had to dig to find a lot of staple effects ramp, removal, and card draw on Legendary cards, most of which are permanents because there are barely any Instants or Sorceries