(It can't be the target of spells or abilities your opponents control.) If Karakyk Guardian leaves the battlefield and returns, it's considered a new object even if it's represented by the same card
However, there's another unusual Pokemon that claims the crown from this original
1x Full size, two-sided Poster of the Original 151 Pokemon on one side, and all the card illustartions of each pokemon on the other side
Put a +1/+1 counter on that creature for each 1 damage prevented this way
Heres a full breakdown: Beginner Solo Battle First Time Rewards : 2 Pack Hourglass, 1 Promo Pack B Series Vol 5, 1 Shop Ticket, and 25x EXP
As we saw from Disallow, planeswalker ultimates are basically the best thing to Stifle in Standard these days, but you wouldnt play such a card just to do that