Ok ummmm when I use my item finder by cerulean cave it points to it but..

It is a Beserk Gene, it is in the water so you need Surf.


P.S. I forget what it does but it is a hold item.

Hope I helped!


Super Luigi out!

You need to surf up bu Nugget Bridge. Over along the side of the cave (where it looks like an upside down 90 degree angle), press A and you should fing a Berserk Gene. I don't know if it is a one-use item or a hold item, but it works like the move Swagger (raises attack by a lot but causes confusion). It might come in handy but I never used it...

~Max_300

The previous answers are true,it is the beserk gene and it does work like swagger but the true purpose of it is to get mewtwo through trade from blue or red then have him hold it and supposedly it basicly super-ultra-turbo boosts his power becuase supposedly it's a missing part of his body that got ripped out/off of him and made him weaker And*emphasize on and* it canceles out the confusion part of the whole swagger deal but I hav have never been able to try it because I have never been able to obtain a red or blue.A friend has told me it is a better version of the twisted spoon whisch boosts psy-type moves.Hope all of this somehow helps you,good luck!! Youll need it!!=)

The above answer saying that Mewtwo cancels out the confusion is wrong. Your Mewtwo will still become confused when he is holding the berserk gene.

Is there any way to catch mewtwo in Pokemon crystal ? Without cheating of course