u cant

i forgot how i got mew but u have to trade from red or the other ones to get mewtwo

go on to pokemon red cheats and it will show you

First of all, Nintendo didn't make this intentionally so that people can get Mew. This is a code, or otherwise a glitch in the game. The only true method of getting Mew is getting Mew directly from Nintendo, from their promotions. However, GameShark (a cheating device) may be used to get Mew (warning: GameShark may cause problems to games). And of course, this code/glitch can be used to get Mew. This method has been proven safe by many. Nevetheless, using any code/cheat/glitch should be used with caution, you are taking a risk of causing a glitch that you may not like to have. Use at your own risk.
Now on to preparing to get Mew...
For this code to work, there's some important things that needs to be followed. If you already finished the game, chances are, there are things you did that will cause this not to work. So most likely, if you finished the game already, this cheat won't work. And you'll see why in the below preparations in orderr this to work.
Make sure you follow these instructions carefully. This code works for Red, Blue, and Yellow versions. Do NOT battle the trainer at Route 8 and Route 25. If you do, the code will not work. You need to play the game from the start till the point where you get HM02 Fly from Celadon City. At that point, you can do this code. Also, make sure you have a Pokemon that knows fly with you while doing this code.
Go to Route 8, and stand in front of the door in the building shown above. Be careful, to move so that the trainer near the house can't see you. This would be a good time to save your game, because you can't save the game until you got your Mew, and you may mistakes, so this will leave you at a good point to start over.
When you take a step down, that trainer will see you. However, when you are taking that step down, quickly press start. If you did it right, then the menu should pop up first before the trainer can see you. If you didn't get it right, then you'll have to start over. Because you can't battle this trainer. Battling this trainer will ruin the code.
Now go to the Pokemon menu, and using the Pokemon that knows fly, fly to Cerulean City. The trainer will see you. But don't worry, it's normal. You will fly off to Cerulean City before that trainer can even battle you.
After going up the Nugget Bridge, go east towards Bill's House. You won't actually go to Bill's House, but along the way, you need to find the trainer seen above. This is very important: You have to make the trainer walk up to you. So don't go in front of the trainer, it will cause your game to freeze. Walk above the trainer, so that he has to walk over to get to you. Once he walks over, and meets you, then you'll have a battle, and you have to win. It shouldn't be a problem, the only Pokemon he has is a Slowpoke at level 17. After you won the battle, fly to Lavender Town.
Ok, you're almost there. At Lavender Town, go to the path seen above. Take one step towards a path, and the menu will automatically pop up. Exit the menu and you will immediately encounter Mew. Mew is only at level 7, and only knows Pound. So it shouldn't be hard to capture.

You go to Cerulian City on Red, don't go in the gym or to Nugget Bridge.
Go beat everyone on nugget bridge, but don't fight the trainer in the grass.
get an ABRA. save right before you face the trainer. quickly press start right as the trainer sees you. make your abra teleport back to the pokemon center. Everything should be jammed other than the walking thingy. go in and verse the swimmer in the Cerulian Gym. then walk up negget bridge and a mew will say to you,
"You would be a great leader of team rocket." the exact same as the guy who gives you the nugget. then a level 7 Mew pops up. you have to put it under a special condition like I used sleeppowder on it. and lower it's HP. then catch it with a pokeball.

to get mew battle every one in cerilian city exept the dude in the grass next to the brige on the right and the yonugster with slow poke. save ur game just befor u battle the dude in the grass. when u go to battle him dont talk to him in fact u dont battle him at all u press start quikly befor the ! comes up on his head. P.S U NEED abra that knows telaport!!! USE TELAPORT to go back to the pokemon center ur start button does not work if it does start the cheat over again. now beat the yonugster with the slowpoke and telaport again. now ur start button is working again. go back to nuget brige and the first step u take ur start menu pops up press B and u will battle mew. TRUST ME THE MEW IS LEAVEL 7 AND ONLY KNOWS POUND HAVE FUN WITH MEW I DID.

.0.0.0.

hi you wounder of the cheats for mew and mewtwo here it come.
mew 0197edd0 mewtwo 0196edd0 . this cheat are for

Mewwo - trade zapdos , articuno moltres - must be gold version , go mount silver , look up
mewtwo n gold on youtube follow the guys instructions , if celebi doesn't warp you u need
more badges or its not the right time , you basically fly to azlea town but end up going
to new bark cos celebi takes you back in time to catch mewtwo because he is causing a
problem and he knew where hew ould be that day and no matter if you use a pokeball , cos
celebi is watching he uses his powers to change your normal ball into a gs ball for a
guaranteed catch all in the blink of an eye if you do it right , note you don't see celebi
at all but its the engish version or cut down events for mewtwo as the jap game has a more
fuller event for him and silver has a more fuller event for the kanto birds and a mew egg
if i am correct , icould be wrong and they could all be in all of the gen 2 games but i
have a hundred percent got mewtwo that way flying from the right spot pressing and holding
b an a with the 3 birds traed must be from yellow version or wont work and you cant just
use a gameshark code even if you change your id and their ids with a gameshark it doesn't
work , the game notes where each separate pokemon is caught and traded have ther location
met in the pecial maps or time machine map not normal location maps its how it knows if
you cheated and if you do it doesn't give youextras those weeks later when youv done
certain tasks or not done cerain ones in the case of articcuno and co its really hard
getting one of those lot let alone them all , rememberhow many sidequests and timed events
their are ... Thers over 340 maps and 8 or so you wont see til you get that far , that
single event itself will probably get you a gs ball somewhere dwn the line at the train
station from that woman if im honest - this isn't a lie mewtwo is really on rt 29

Oh and celebi , you need to start a new game with fergalitor , take the berry straight
away , do not buy any items from shops at all , aprt from pokeballs , put the 5 from elm
in the pc and any others you find hidden on the floor or in item balls , collect a berry
from every tree atleast once get every tm and daily item in the game starting from sunday
to sat in that order , you r first pokemon you catch has to be a pidgey nothing else will
do , then get a old rod get a majicarp , evolve and train it in your squad of 3 , when you
have 4 badges you must catch a tauros as your 4th pokemon , you need to walk round
sudowoodooo and some other stuff to do this with walk throguh walls somethimes but its ok
you need to toget the celbi time travel - yep you read right - time travel event , then
you later get the red gyrados next to make up for the possibility slim as it is of it
turning up blue at the lake (imagine a shiny reset but for a non) this chance is overseen
in the method by this you see , then the next is a dratini , train these all to level
hundred imt sure if you have to stay at 8 badges now or go to 16 but the far right of ilex
forest will now contain a spearow with cut , i m not sure which 1 on the right this is 12
year ago i did this some1 told me and i saw something about headbutt probably headbutt all
trees with pokeflute fm on , i do remember to talk to the shrine toss 5 items and use cut
it should appear lv 50 wih psycchic , teleport , mimic and recover i think it is so bring
a masterball do yourself a faver invest in wobbuffet and mod his moves with a shark , dont
cheat get all items put em in the pc take em with you to the fores talk to the woman and
kurts statue on the way and complete the entire okedex first you find a mew egg this way
so you can at 150 and you get a mewtwo event after i do beleiv and a zapdos 1 and stuff
covered in no guides , thats pretty much ll i remember but with those tips you should pull
off celebi , mewtwo the lot , ps thers a vid on youtube showing you mewtwo ncounter

Thers a time travel event and a ld celebi you need to see before you can get mew/mewtwo
... Word of advice , if you trade in legendary birds , don't trade in mew or even catch
him from yellow cos the link cabe lts gold know if you cheated on the other game and it
looks at your pokedex and looks in the gen1 games coding to see if an event mew is inside
and if not then it stops you getting celebi , mewtwo , mew and the wild legendary birds
and wild blastoise and kabutops in gen 2 , note people who have tried the lv 100 thing and
not seen celebi with 249 pokemon haven't imported 150 from past , have probably cloned or
cheated in that save , you cannot cheat 1 bit all numbers 1 to 150 from time machine in
pokecentre and save all those items you get , you don't have to keep them 150 in the game
, just get their entrys , it is 149 sorry not 150 cos that's how you get ewtwo pear in the
game , i was wrong , it actually is in cerulean cave but you must time travel and get
celebi with the level hundred johoto legendaries in your party , that is silver version
gold is difrent