no they are not i no i thought they were at first not but they not related
No, Deoxys is only in Emerald, and you need to migrate it to can catch it. As for Celebi and Mew, you need a cheat code for them.
you can`t you have to trade them in from the pal park
need to get their events
You can't. It is received in a Pokemon event, like mew and Celebi from the other games.
Celebi is known as the Time Travel Pokemon because of its ability to travel through time just like Dialga.
It's not possible to capture Pokemon so no. You can unlock pokemon like Mew and Celebi.
In an Event. The same way to get MEW and CELEBI
You cannot catch Mew or Celebi in the wild, for they are event-only Pokemon. Events for Black 2 and White 2 or previous games are no longer distributed, so an Action Replay or a GameShark will be required to encounter these Pokemon in the wild. (Do not encounter Mew in the wild in Pokemon FireRed, LeafGreen, Sapphire, Ruby, and Emerald, (Unless in Faraway Island) for it is programmed to not obey, regardless of how many Gym Badges the player earned.) Mew is an exception for 2 ways. You can perform the "Mew Glitch" in Pokemon Yellow to find it east of Lavender Town or you can have 999 Pokemon in your Pokemon Farm to get Mew from Hailey. Celebi can be found doing the "Celebi Glitch" in Pokemon Gold, but it is a lot more risky and harder than the Mew glitch mentioned above. You may want to research these glitches to get the accurate answer.
Mew
i want to trade celebi for a entei
that would have to be Celebi or Mew, the only possible way to get them is if you get a Japanese version of them.
the Unobtainable Pokemon in RSEFRLG are Celebi, Mew, Jirachi, Deoxys, and 000 (Missingno. ( DO NOT ATTEMPT TO CATCH))