Press space. scroll down for timeline explanation. PMD2 SPOILERS AHEAD! Celebi grows and gains memories like we do, but it can travel to a point when it already existed. If someone called Celebi, their Celebi, Celebi from any point in the past, or Celebi from any point in the future could answer. So it's easy for Celebi to help me pull pranks, but future Celebi may say he/she (the shiny is a tsundere in the most one-sided relationship of mystery dungeon and female but genderless... dunno how it works.) already did so, and if I say so to Celebi, he/she will be like "gotta do that later" and I guess that's it. Now with PMD2's space-time incidents, there's no marking for how time flows, but if it messes up, Dialga could go Primal, wishing to "get rid of" those who mess with the timeline because it means the destined future shall vanish. And by "get rid of" I mean literally send a bunch of Sableye led by a Dusknoir to KILL you. You know, for kids. I have seen timelines made for Mystery Dungeon, but I think they all happen parallel to each other, somehow infusing in Super Mystery Dungeon. The time travel timeline works almost like Celebi's timeline. If someone was attacked, they may separate from a group and definitely will be forced to spend Peeko knows how long with amnesia. If a human was attacked, they would not only reach their correct time (however many years back or forward they need to travel, they'll reach the exact time) with amnesia, but the incident will also turn them into a Pokemon. This could cause a mess, especially if they forget about their will to sacrifice themselves to change the future.
Images not mine. I'VE BEEN PLAYING TOO MUCH SKY SO LET'S JUST ADD A THEORY ON THE DISTORTION OF TIME. Bidoof went to Jirachi, wished for a buddy or two, Jirachi went to the past with a time portal, made sure a partner Pokemon would survive, asked Darkrai to mess up space-time, went back, you came from the future, and everything else happened. god im hopeless and have no life also my arachnophobia returns so wow lol