The Salamencite quest is the quest done in order to receive the Salamencite. This quest was exclusive to the Valentine's Day event.
To make the quest go as smoothly as possible, these preparations should be made:
To begin with, you need to reach Aphrodia Island. This can be done by speaking to Sailor Jenny in any port town—Vermilion City, Olivine City, Lilycove City, and Veilstone City. If you have completed the first part, Mayor Shiro will greet you at the beginning of the island and inform you of another issue. Once you agree to help her, you will be introduced to Ranger Ayva. After this, speak with Sailor Jenny and she will have an option to go to Nido Isle—your next destination.
Once you've arrived, head to the southwest part of the island and speak with Ayva. She will ask that you help her with calming down and tagging the Nidoking and Nidoqueen; there are 10 of them in total. A few of them will battle you and some you can calm down using a status-inducing move. After all the Nidoking and Nidoqueen have been tagged, return to Ayva. She will mention that there is a certain Nidoqueen looking to a far-off island. She suggests you go investigate what is happening over in that island.
After arriving, make your way towards the middle of the island, and Ayva will be there next to a Valentine's form Jellicent. Speak with the Jellicent then with Ayva. Ayva theorizes that the Jellicent and Nidoqueen are in love and tells you that you must help them. Follow Ayva to speak to one of the other conservationists—Aphelios. He will dismiss Ayva's plea to help the Pokémon.
Not giving up, Ayva devises a plan to help the Jellicent and Nidoqueen meet each other. First, she will ask you to collect something to lower yourself to the next area. This item is called "Rope", and is guarded by Frillish in the overworld. Your task is to collect 5 Rope. However, the Frillish, similar to the Nidoking and Nidoqueen before, will either battle you or require the use of Sing or Tickle. Now that you've collected the 5 Rope, return to Ayva. She will move forward with Jellicent and you are to go get the Nidoqueen back in Nido Isle.
The Nidoqueen you need to get is inside Nido Barn on Nido Isle. After speaking with Nidoqueen, she will follow you; whenever you are in front of her, she will move towards you. Guide her to the Valentine's form Drifblim on the southern part of the island, near where Ayva originally was. Before you are able to deliver Nidoqueen, a level 90 Nidoking will attack you.
Once that has been dealt with, you are to meet Ayva in a new location called Dragons Neck
Now that you've arrived in Dragons Neck, find and speak with Ayva. She tells you she will go on ahead and will be waiting for you on the other side of the island. You must now go through the cloud maze. If a ranger sees you, you will be teleported back to the beginning of the maze. After you pass the first 5 clouds, you will get a prompt saying the clouds seem unstable. From this part, the rangers at the beginning will no longer move. You will need to move fast because the clouds will "fade" and you will have to start the maze again.
After making it through the entire maze, head to the easternmost area. Atop some stairs, Ayva will be waiting. Ayva mentions that Salamence may be ale to take Nidoqueen and Jellicent away to a safe area, but it is not able to do so in its current state. Ayva says Salamence needs its mega stone to be powerful enough to take both of them away; she explains Mayor Shiro may have possession of the stone. Swiftly, Mayor Shiro appears and confirms her possession of the Salamencite. She questions your ability to control Mega Salamence and challenges you to a fight to prove your worth.
All NPCs cool down after 7 days unless noted contrariwise.
Upon defeating Mayor Shiro, Salamence will mega evolve and be powerful enough to take away Nidoqueen and Jellicent. You must now wait for Salamence to return, which will take approximately 10 minutes. After it has returned, speak with Mayor Shiro and she will bestow onto you—the Salamencite. Remember that you will need to have the Mega Bracelet in order to claim the Salamencite.