Cynthia

Overview

Much like the protagonist, Cynthia started her adventure into the world of Pokémon by being given a starter Pokémon and  Pokédex by Professor Rowan. She appears to have a keen interest in mythology of legendary Pokémon  and her family live in Celestic Town. In Pokémon Diamond, Pearl and Platinum versions she aids the character at one point in fighting Team Galactic, appears on route 214 after the player has defeated Crasher Wake and gives the player the Secret Potion on route 210 to enable them to pass the Psyduck blocking the way. In Pokémon Platinum version she also assists players on their journey through the Distortion World and upon exiting the Distortion World she tells the player that although she wishes she could have battled Giratina the events within the Distortion World were destined.
 
Cynthia appears at the end of the main storyline as the  Pokémon Champion. Before the battle against her begins she gives the player a short speech on their journey through Sinnoh and how powerful they have become and in Platinum version she will also thank the player for their help on Mt. Coronet and in the Distortion World. After she is defeated she will announce the player has become the most powerful of all Pokémon trainers and is the new Pokémon Champion. In Platinum version after defeating Cynthia the player can find her in Celestic Ruins where she will give them a long speech on the cave painting within the ruins and the mythology behind it.
 
In Pokémon HeartGold and SoulSilver versions if the player has a fateful encounter Arceus (a special type of Arceus only given away at Pokémon events) as the first Pokémon in their party they will be able to access the Sinjoh Ruins in the Ruins of Alph. Inside the ruins Cynthia can be found researching the legendary Pokémon that originally appeared in the Sinnoh region and upon interacting with the player she tells them that she senses something is going to happen at Mystri Stage. At Mystri Stage Cynthia can be found and if the player has an Arceus and no other Pokémon in their party she will them the choice between obtaining a level 1 Giratina, Palkia or Dialga. 

 After finishing the main story of Pokemon Black/White, she can be challenged. This time, it seems she has added a Braviary to her team. 
Gym Leader Elesa visits Cynthia in the summertime.