The serum you are talking about is actually called a secretpotion. You have to go to Cianwood City's pharmacy. Once you talk to the clerk, he'll give you the secretpotion to give to the Ampharos in the lighthouse.
You can only get the SecretPotion after you have talked to Jasmine in the Olivine Lighthouse. Then she will ask you to get Ampharos some Medicine. You go to Cianwood City and talk to the guy at the Pharmacy and he will give you SecretPotion for Ampharos.
After you have defeated leader wake in pastoria city, Cynthia will give you a secretpotion, go to the psyducks and they will go away
you go to lake valor, where you'll meet the Pokemon master Cynthia. she'll give you the secretpotion, which you spray on the psyducks to get past them.
After the explosion at the Great Marsh, follow the Cyrus and beat him. Then Cynthia will give you the SecretPotion, which makes the Psyduck's heads feel better and makes them move.
to the pysducks ;)
To get the secretpotion, you first have to have talked to Jasmine. She will then direct you to the Pharmacy in Cianwood. If the guy does not give it to you, then it means you have to beat Chuck first.
The serum you are talking about is actually called a secretpotion. You have to go to Cianwood City's pharmacy. Once you talk to the clerk, he'll give you the secretpotion to give to the Ampharos in the lighthouse.
go 2 cianwood city's pharmacy.the man at the counter will give u a secretpotion after u have seen amphy(the sick ampharos in the lighthouse)
A house in Cianwood has a guy who give you a Secretpotion. Use it on ampharos.
you are going to have to surf to cinnabar island and there will be a pharmacy there. talk to the guy and he will give you the secretpotion for free
You can only get the SecretPotion after you have talked to Jasmine in the Olivine Lighthouse. Then she will ask you to get Ampharos some Medicine. You go to Cianwood City and talk to the guy at the Pharmacy and he will give you SecretPotion for Ampharos.
there is not a secretpotion in Pokemon silver Daniel robertson
You get it from the genie that you meet in Jubilife City if you do not see the genie then you must return the game and ask for a full refund immediately, but before you can see the genie you need to release your starter Pokemon.
i went to the pharmacist because i had a lip rash
First of all you have to go all the way up the Lighthouse. It is a large building in Olivine City. When you come to Olivine it is at the far right of the city, just by the water. You can't miss it. Talk to Jasmine, who is on the top of the Lighthouse. Then go to Cianwood City across the sea and talk to the pharmacist and he will give you the secretpotion. I know this works for gold, because I just did it today.
The secretpotion does not exist in SoulSilver, due to there being no use, therefore this question is void.