To be honest even in the games its said that taking the island challenge is a rite of passage. With the number of side characters who seemed to have taken part I never thought Z-crystals were supposed to be rare. That being said I would have preferred it if Hapu only had a specific crystal to give away instead of letting Ash choose.I wished the Sun and Moon anime emphasized more on how rare Z-Crystals were than they did. I realize some Z Crystals are available via finding them on the ground but I felt like the scarceness of them were taken away once adapted into the anime. I think the most jarring part was when Hapu pulled out an entire box of them and just let Ash/Pika choose.