While the counter on its own is a one time thing, having this trigger at the beginning of combat and then the ability to get that creature back with haste for that same combat makes a very tight window for opponents to deal with your shenanigans
Check out all 31 of the new-to-Magic cards below: For a list of all 787 cards in Jumpstart: Historic Horizons go to the bottom of this link and open the drop down menu.
To exploit this, flicker the defender creatures to draw large amounts of cards
You remove a threat, sure, but you also see their entire plan
Even better, these are set up so that kids can keep printing them up and designing Pokemon any time of year, not just Valentines Day
So if Pokemon ever prints Psychic-type acceleration, then you're absolutely going to be running Hoopa in that deck, almost definitely