The idea of bringing back old events isn't that bad but using mystery boxes to bring them back is not fair in some ways by reason is that many people in game don't buy mbs because they cost real money and the they can't afford it, even though people who can afford them,have an advantage over those who couldn't. There should be some other way to bring back old events for example, there are some kind of battles like sidequest and after hitting a certain amount of battle u can get a random deoxys,volca,arceus's,etc. I guess it will be more fair like that.