What games do you need for all the Johto&kanto pkmn

[shardwing prime]

Ok. I have gold and blue and need to know what else I need to get all 251 or 249 pokémon.Like, could I get the other pokémon with just crystal,etc.

[Poryhedron]

Let's see...here are the pokémon you can't obtain with Gold and Blue:

Ledyba/Ledian
Phanpy/Donphan
Delibird
Skarmory
Celebi
...and if you don't feel comfortable exploiting glitches, you can add Mew to the list as well.

Also, you have to worry about getting all three of Chikorita, Cyndaquil and Totodile...the choices to make in Blue aren't a problem because you can store your Blue pokémon on Gold, restart Blue and take the other one, but you can't do that with the choices on Gold because you can't store all of your Gold pokémon on Blue.
Crystal Version would solve the GSC Starters problem and also allow you to catch every pokémon on the above list except Celebi and Mew. For Mew, you can exploit the recently discovered glitch in Blue, but Celebi answers only to Game Shark and similar "video game enhancement devices".

[Knight of Time]

I know of a little trick for getting all three starters on Gold and Silver, but there's a catch to it, which I'll explain shortly.

First off, you need to be at the very beginning of the game. Save just before you go to pick your first Pokemon. Now, whatever you do, DO NOT save your game after you get your starter, or this trick will be ruined. Without saving, play until you beat your rival in your first battle with him, and after you get your Pokeballs, go out and catch a Pokemon (it doesn't matter what Pokemon you catch). Now, this next part can be a little tricky. Go to a Pokemon Center (preferably the one in Cherrygrove City), and deposit your starter into another box. Change boxes. As soon as you see the message "Saving...don't turn off the power", turn off your game, and turn it back on again. Remember, if you didn't save at all after getting your starter, you will be back in the lab. From here, you can repeat the trick, effectively getting all three starters with just the one Game Boy (I did the trick myself successfully a couple of years ago). But, here's the drawback to the trick. When you get the third starter, you will not be able to see the data for the other two starters AFAIK, and I believe you have to evolve them to be able to see their data (either that, or trade the Pokemon to another GSC game and back). Of course, if you don't understand this trick, you can always go to David Wonn's Video Game Glitches (just look it up on a search engine, and you should be able to find the site easily). That's where I learned this trick.

[shardwing prime]

Thanks.Now I don`t have to get silver,red, and yellow to complete my pokedex.Might still get yellow though.And crystal of course.

Also, I already have a celebi, I got it with my brother`s gameshark, but I prefer to limit my cheating.Plus the shark is broken now...