I have been playing pokemon gold for over a year now and I REALLY need..

Ok, for blissey you have to get a chansey and become great frinds withit (like you did with your eevee to get umbreon and espeon).

Next I believe quilfish is one of those rare pokemon that come in swarms if someone calls you,
as for the last two you have the best chance buying a gameshark and getting codes for them.

If you cant find the right gameshark for the game then go to a pawn shop .

They sometimes have a pretty good selection!

Blissey: Have Chansey's friendship peak
Qwilfish: Register Fisherman Ralph's number and go to Route 32
Mew and Celebi: These days, only through cheat devices

To get a Blissey do 1 of 2 things: Either capture with Chansey with a Friend Ball (hard but do-able) and train it or catch it witha regular ball and train it with giving it haircuts.

After this, it will evolve into Blissey. I think you should do the friend ball technique. Just save if you're going to do that way.

To get a Qwilfish, get Fisher Ralph's phone number and then he'll call you and say the Qwilfish are biting like there's no tomorrow.

Then just use a good or ultra rod and you can catch qwilfish.
To get Mew either use a gameshark code (0197EDD0) or trade from a red/blue/yellow version.

To get Celebi you HAVE to use a gameshark code (01FBEDD0) or a Nintendo Pokemon game. Hope these help you.

Blissey evolves from chansey when it is very happy any level after lvl 40.

Qwilfish can be caught on route 32 above Union Cave by using a super rod HINT: use a lure ball that you can get by giving a blue appricorn to Kurt.

Mew has to be traded from red,blue,yellow or gotten by gameshark codes.

And Celebi can be got by gameshark or by getting all 250 pokemon and all the unown forms and go to Ilex Forest Shrine. Can't tell you much more on Celebi...

Good Luck!

Well I got a celebi wit out a gameshark you need to caught a sneasel and make it grow to level 57 and have the move beat up in the third move and then you got to go to the guy and get his name switch 2 cccccelebi and you got 2 clone 5 of them and one bad one and you have 2 have on Pokemon and out of you're in boxs and then you got to give them 2 the day care woman and the man and get them back

To get celebi without a game shark(this really works)

You pause the game & while on the start menu walk into your bathroom & stick your plunger handle up your all the way to the suction cup part. Then go to route 35. Have raikou last & umbreon first. Use cut to get rid of all of the grass but one square. Make sure you have lots of ultraballs. Fight 3 pokemon. Run from the last one but you need to hurt it first. The next Pokemon you run into should be a celebi & level 5.

If you accidentally kill it it's cool. It jumps from route to route on the pokedex. You can find it again.

To get celebi ( this actually works)

Catch enti, suicune, & raikou. Have them in that order. Go to route 35.save. Press start select a& b all at once. Do that 3 times. Then use cut with tyranitar to get rid of all of the grass but one patch. It has to be tyranitar & all of the grass around or it won't work. Now walk in that grass. After 3 Pokemon a wild celebi level 5 will appear. It will use roar. Switch to a Pokemon that knows mean look. If it gets away the first time it's fine. It jumps place to place like the legendary dogs do so you can run into it again. IT IS REALLY HARD TO CATCH. So keep a masterball or have 99x ultraballs.