What you do is you go into the Pokemon Center in Viridian city, talk to Jigglypuff, talk to the man next to jigglypuff, then walk to Nurse Joy, say cancel instead of heal, walk two steps away from Jigglypuff, walk back, and talk to it, and it will make your last Pokemon fall asleep! Note: Sometimes it wont work, so dont be dissapointed if it doesnt. It will work soon.