you can but i prefer the master ball.this is because the ultra ball wont work as well.

you can us any ball on mewtwo

dont waste your masterball on mewtwo, use it on the Pokégod...

oh yeah, this is how to get the Pokégod.
once you have got surf and the item finder go back to cerulean city(where you fought misty) and surf along the water where you would go to the unknown dungeon(cerulean caves) and use the item finder, it will say there is an item nearbye. swim around pressin A and you will eventually find a mysterious item. take it to professor oak and he will tell you about it. then surf down to cinnabar island and go to the ressurection lab(where you would give old amber and fossils) they will just take it straight off you and tell you to go away. you cannot go back into the room untill you have all 8 badges, and mewtwo( getting mewtwo without the master ball is extremely hard but its worth it). after you have done this go back to the lab and no one will be there and it will look all wierd, like it was destroyed or something. then the screen will go black like when you run into a wild pokemon and mewtwo will pop up. it will say that he no longer needs your assistance and he will run away. then go to the ressurection machine and the mysterious item will fall out. pick it up like any normal item and the screen will flash black again but this time it will be amber of mewtwo. then writing comes up on the screen looking all weird like this; ╔yíñ±┼○ã▲ñ but different(still wierd though). then, it just all goes blank and the music will stop. you will end up at the at your house looking like when you first started. go up to your mum and the screen will go black(yet again). mewtwo pops up again but this time there is two of him but only one comes up at a time. first the one in the amber and it will crack open the screen will flash and the second mewtwo will appear, he looks different from the normal ones because he has three eyes. then it will flash again and the first mewtwo wil appear, it will flash again and it just keeps getting faster and faster and then it goes blank again. the two mewtos will have fused, and it will say he still requires your assistance...
you will end up with him(or them should i say)but its name will be wierd again. he has double everything(including attacks so he will have 8) and double stats. he doesn't have a lvl, all it says is ...
after this go back to the first gym and brock will challenge you again only this time he has 6 mews all of them lvl 100. he steals all your other pokemon(the ones on you and the ones on the pc) and then uses mysterious item on mew.
you say: where did you get that from? and brock says: it came to me from the pokégods. you say: what are the pokégods? and then the screen goes blank(again)you will end up in the hall of fame and there will be a door infront of you, go through it and the a wild pokemon appears, its your fused mewtwos. he says: i am the pokégod...

THERE IS NO SUCH THING AS A POKEGOD!

yes you can a good way to do it is to either put it to sleep and weaken it thenuse an ultra ball(you can use this for legendary birds too)or just use a masterball.

submitted by(zachary rutledge)

"y do i need a usrnm" i used my itemfinder in da water and it did pick up a item but the only item it pikd up was a rare candy located behind the dude that tells u about bages house. so dude if u could plz message me and b more precice on the item location that b great...unless ur just makin it all up...

you could, but a masterball would be much easier, because you catch it right away, and the ultra ball may not work