I agree to g3n3r4l here, you could bind that item to the account (or in his argument, the pkm that has been pinkanized). To the other concern, what would be wrong having a few godly pkm pink? Noyone is forced to buy these! It would not wreck the economy, lets be real here, how many people do you know who have done this quest in first place? It would be so hard to obtain the berry (or whatever other reward), how is it not justified to give a pokemon a lot more value for collectors? I really dont get your point tbh, no offense. I mean, if you think it was that easy, go ahead and grind yourself that pink pancham, good luck.
But also, to both of you, if the pokemon were sellable, explain to me how the economy would wreck if there were 20 godly pink pokemon around. How many godly pvpable pkm are out there, do you really want to tell me if 20 of these were pink and higher in value, that the economy would be wrecked?
It was a suggestion of an idea that ran through my mind, something that I would find rewarding that would also fit the whole theme of pinkan island. It is not an either or, fact is, for me, that the reward for that quest is simply very unsatisfying.