You know, I found that Wish Cave is the easiest of 3 Lv1 dungeons
(when mentioning the goal when you enter the dungeon): Huge Apples, item allowed, Pokemon with average power and average Exp. The second one is Purity Forest: although you can't bring friend, no item, but Pokemon there are relatively low in power and high in Exp. The hardest is Joyous Tower: despite stats drinks, item allowed, Pokemon are high in power and low in Exp, and Pokemon are hard to find.