Its called the Cinawood Medicine. U need to surf to Cinawood Island, go to the pharmacy and collect the medicine. Then go back to the lighthouse where Jasmine is waiting and give it to her. She will give it to the Pokemon and will let u battle her.
First, I must tell you that you cannot buy the medicine needed for the Ampharos in the lighthouse. Surf to Cianwood City, which actually is an island, there will not be a Pokemart, but there will be a building that you must go into. Go into it, and talk to the guy at the front desk. He will give you the medicine.
GUIDE:
Step 1. Cross Routes 40 and 41 to get to Cianwood City. In here, get the Secret Medicine from the Cianwood Pharmacy.
Step 2. Head back to Olivine City and climb the lighthouse. Battle all of the trainers (if you have done this, then take the elevator up).
Step 3. Give Candace the Secret Medicine and it will heal the pokemon.
From route 40, surf south until you reach route 41. From there, surf west and you'll arrive in Cianwood City, which has the Cianwood Pharmacy that contains the medicine to heal Amphy. Buy the SecretPotion and surf back to Olivine City. Go back up and give Jasmine the medicine.
You need to purchase the medicine in a pharmacy, situated in Cianwood, an island. You need the Surf TM, by defeating Team Rocket in the Dance Theater in Ecruteak City ( a gentleman hands you the TM ). You get the medicine and she will administer it to her injured Ampharos, and also she will let your character battle her. She is a Steel - type. E.g. Use Fire type Pokemon against her.
I hope I helped you.
I know this because I have played Soul Silver and I consulted a walkthrough, which you should use as a source :)
surf to cianwood city from olivine city and go to the mart that's to the left of the Pokemon center.
use surf to go to cianwood town. There someone will give you a mysterious potion.
you need to get a special medicine from the drug store in cianwood.
You go to the pharmacy and talk to the guy inside. He will give you a potion to heal the Ampherous inside the lighthouse. Go to the top and give the potion to Jasmine. Then you go to the gym and verse Jasmine
by pressing 'a' on it and if you have an Oran Berry, it will give it her.
Surf to Cianwood city and go to the Cianwood City Pharmacy. Talk to the guy in there and he will give you the medicine.
First, go to the top of the lighthouse (not by the elevator, but by the stairs) to meet Jasmine and be told that you need a secret potion from Cianwood. Go to the Cianwood Pharmacy to get the potion. Go back to the top of the lighthouse and talk to Jasmine to give the secret potion to her.
You give it back & she will give you the magnet train pass.
You must surf on Routes 40 and 41 to get to Cianwood City. In the city, there will be a pharmacy where you can get a Secret Potion. Give this to Jasmine.
I have HeartGold and in Cianwood theres a store there and go in and he'll give you the SuperPotion or something like that. Give it to Jasmine and then Ampharos will light up.Pokemon soul silver the Pokemon in the Olivine City Lighthouse Needs medicine, you can get the medicine in the Cianwood City and you get it in the pharmancy next to the medical center
You must first talk to Jasmine, located in the top floor of the lighthouse. She will inform you that Amphy needs medicine. Then, go to Cianwood City. The medicine you seek is in the pharmacy there. From that point, give the medicine to Jasmine, and battle her to get the 6th badge.
First, go to the top of the lighthouse and talk to Jasmine about the potion. Then, surf west towards Cianwood. From there, head to the medicine shop. The man will hear about the story and give you the potion.
You surf to the left of the island until you get to cianwood city and go into the medicine mans cabin. Once you talk to him, he will give you the medicine and you can either fly back or surf back to the lighthouse to give jasmine the medicine.
You must first reach the top of the lighthouse. Once at the top, you will have to give her the Secret Medicine. Here's a short guide.GUIDE:Step 1. Cross Routes 40 and 41 to get to Cianwood City. In here, get the Secret Medicine from the Cianwood Pharmacy.Step 2. Head back to Olivine City and climb the lighthouse. Battle all of the trainers (if you have done this, then take the elevator up).Step 3. Give Jasmine the Secret Medicine and it will heal the pokemon.
You must give the Secret Medicine, which can be obtained at Cianwood City.
You go to the pharmacy and talk to the guy inside. He will give you a potion to heal the Ampherous inside the lighthouse. Go to the top and give the potion to Jasmine. Then you go to the gym and verse Jasmine
no you can trade soulsilver pokemon to black
First off, you won't be saving her; you will be saving the sick Ampharos. You have to give her the secret potion at the top of the lighthouse. Here's a short guide.GUIDE:Step 1. Cross Routes 40 and 41 to get to Cianwood City. In here, get the Secret Medicine from the Cianwood Pharmacy.Step 2. Head back to Olivine City and climb the lighthouse. Battle all of the trainers (if you have done this, then take the elevator up).Step 3. Give Jasmine the Secret Medicine and it will heal the pokemon.
In Pokémon SoulSilver, you get the Mineral Badge from beating Jasmine the Olivine City Gym Leader however in order for her to return to her Gym, you have to go to her in the Lighthouse and walk up the stairs to her. She'll tell you the Lighthouse's Ampharos is sick and that there's medicine in Cianwood City that will cure it so you have to head to Cianwood City in order to retrieve the SecretPotion from the Pharmacy there and then you can give the SecretPotion to Jasmine.
Go back to Olivine City and give the medicine to Jasmine. Then fight her at the gym.