My friend says that he will trade me a Celebi and Jirachi for my Lv100..

Don't trade with him, he's Pokemon are fake!

Sorry, Pokemaniac, they gave out Celebi all over the US last year during the 10th Anniversary Mall Tour-that's why I bogused your answer, sorry again. I have one, so I'm sure they did, but the one he has given info on is definitely a fake!
To answer the question now: CELEBI-FAKE!!!! The real one's OT would be "10 ANIV" and ID# 00010, Trainer Memo will say it's nature, then the next 2 lines are "Met in a fateful encounter when at Lv 70" It's not legal, but if you want one and don't care if it's "legal" for tournament play or whatever, that's up to you, but you should make him do better b/c that's a fake, I promise, and not from an event! (Though he may have gotten tricked from someone who was trying to trade him since it's so rare, so little info is known, and some people take advantage-he's your friend though, so not my call!)
Jirachi-Well the OT is correct "WISHMKR" believe it or not, but the ID# is wrong. I have one in Ruby, and one in Sapphire, and they have the same trainer ID#20043 from the bonus disc, as would all the other (I just checked one from a different disc than mine, and he's got the same ID#20043, too)so the verdict is:FAKE! It should also mention a fateful encounter at lv 5 in the Trainer Memo part, too. Checking there is always a good way to verify, because it rarely says something like "fateful encounter", usually it's just met or hatched or traded.
So, do you think this guy is trying to get over on you or does he really believe those Pokemon are truly real??? How close a friend? But, a shiny Charizard alone, never mind with Pokerus too!! (be careful, do something quick like clone him before it wears off, it only lasts for a certain period of battles, time, or for so many visits to PokemonCenter for healing, can't quite tell, but CLONE IT NOW!!) Pokemon are only be able to get it once, so if you clone him with it a few times, you can store the clones and you'll be ready to train, trade, whatever. At minimum make sure you give it to another Pokemon who you just put in the PC and you can use to infect others only when you are ready to train them heavily!! You only get one shot to get Pokerus, and I don't think your Charizard can even benefit since he's never going to level up again, but use him to spread it, and definitely do the cloning thing. This way, you can give your friend the Charizard and still keep your own, if you want, and you'll still have the Jirachi and Celebi, just not legal, but I'd make sure the deal is way better than now for you since his are both fakes!!! Make him give up much more or much better if nothing else, and don't tell him about cloning! Or just keep that beautiful Charizard for yourself alone...quite a sight they are! You could always cheat to get them yourself, too, if you can get an AR or Gameshark (cheat devices, one of which your friend may have used) or get someone to do it for you-I could in minutes! They're about $25 depending on where you go.
Well, please take Pokemaniac's advice/instructions for cloning, as you should clone and put him in a different game if you can in case something happens to your game-that would be bad, the Charizard you had! And it's a handy way to duplicate items, too, like Master Balls, etc.!
Hope this helps you, I promise my info is correct, I would even send pictures if I could so you could show your friend the real ones! If he's got a problem or whatever, please feel free to have him post a question, and I'll answer for him. I have real everything, even multiples (different-not cloned) of Flying Pikachu, Deoxys, Mew, Lugia, Ho-Oh, etc, etc., so feel free to ask about info on these guys if you think you see a fake, OK.