Satsuki is exclusive to the The Electric Tale of Pikachu series. Satoshi has a very obvious and powerful crush on her. In fact, his infatuation and desire to impress her by showing up Shigeru is one of the primary reasons he becomes a trainer in that series. Source:Bulbapedia
Lt. Surge is the Gym Leader of Vermilion City's Gym, known officially as the Vermilion Gym. He hands out the Thunder Badge to Trainers who defeat him. He specializes in Electric-type Pokémon. Lt. Surge is an extremely large and muscular man, and seems to be the show's tallest human character. He is arrogant, loud, and crude, and refers to all trainers as "babies" until they manage to defeat him. Lt. Surge generally looks down on unevolved Pokémon, preferring to evolve them as soon as possible. His Raichu shares many of his personality traits, also appearing to be rather tough. Lt. Surge's fatal weakness was that he evolved his Pokémon too quickly without taking the time to teach them the proper attacks. Even though he managed to defeat Ash and his Pikachu once with pure power, Pikachu was able to use speed-altering moves like Agility to get the best of Raichu.
Samurai's sole appearance came in Challenge of the Samurai. Ash and Misty were traveling through Viridian Forest, and Ash intended to catch more Pokémon. He was just about to catch a Weedle when Samurai jumped out of the bushes and threatened him with his sword, demanding to know if Ash was from Pallet Town. Samurai challenged Ash to a battle, having already lost to Gary and the other two trainers from Pallet. In the confusion caused by Samurai's yelling and sword-waving, the Weedle escaped. Samurai insulted Ash, saying that he is a "bad Trainer". Because of this, they started a battle. Samurai's powerful Pinsir knocked out Ash's Pidgeotto, but Ash's Metapod used Harden to damage Pinsir's pincers. Samurai sent out his own Metapod, and the two Pokémon, being unable of using any move besides Harden, were locked in a complete stalemate for hours. Their match was interrupted by a Beedrill swarm, apparently angered by Ash's attack of the Weedle earlier. The Beedrill snatched Ash's Metapod and flew off. The trio hid in Samurai's cabin, where the boy continued to berate and insult Ash, saying that Ash is not a good trainer to his Pokémon, now for how he didn't immediately help Metapod when the Beedrill attacked. Samurai did, however, gain respect for Ash when he used his newly evolved Butterfree to put the Beedrill to sleep by using Sleep Powder. At the end of the episode, Ash, Misty, and Samurai say good-bye, and the two boys say that they will battle again some day. He made a cameo appearance with his Pinsir in the second opening theme, The Rivals, and its English dub counterpart, Pokémon World.
Melanie was the character of the day in Bulbasaur and the Hidden Village. Her Japanese voice actor is Mako HyÅ�dÅ� and her English voice actor is Tara Jayne. In this episode, Ash, Misty, and Brock were on their way to Vermilion City when Misty saw an Oddish. Misty tried to catch it when a Bulbasaur stopped her with a Vine Whip. Ash tried to catch the Bulbasaur, but the two Grass/Poison Pokémon escaped. Ash and his friends tried to keep on traveling, but got caught in a series of traps, including a collapsing bridge, a pit, and a net. Brock fell into the river, but was saved by a beautiful girl named Melanie. She cared for Pokémon who have been abandoned in the forest. Melanie set the traps to try to deter people from catching the Pokémon she cared for. Melanie allowed Ash and his friends to visit her Hidden Village of Pokémon if they promised not to catch any. Melanie explained that Bulbasaur had sworn to protect the other sick Pokémon. Bulbasaur continued to distrust Ash and Misty. Team Rocket attacked the village and tried to steal all the Pokémon, but Bulbasaur and Ash were able to defeat them. Melanie insisted that Ash take Bulbasaur with him, since Bulbasaur wasn't able to grow any in the forest. Melanie thought that the Pokémon were getting too lazy with Bulbasaur to take care of them and they needed to be reintroduced into the wild. According to her, Bulbasaur would agree if Ash battled him; after winning that battle, Ash caught Bulbasaur, and everyone parted ways.
Aya (Japanese: アヤ Aya) is a ninja and a Pokémon Trainer who specializes in Poison-type Pokémon. She is the younger sister of Koga, the Fuchsia City Gym Leader, and is a student of the Gym. Apparently, she was raised by Koga since she was young. She also has interest in poetry. Aya made her first appearance in The Ninja Poké Showdown where they encountered Ash, Misty, and Brock in the Fuchsia City Gym. Aya challenged Ash to a battle with her Venonat and Ash agreed - sending out Bulbasaur. He won the match easily with his Bulbasaur's Leech Seed. After the battle her older brother Koga appeared. Aya appeared again in Ariados, Amigos! where she was training at a nearby dojo, learning Pokémon Jujitsu. She and her Venonat were unable to master it; she even faced Ash and his Bulbasaur in a rematch and lost. But after an encounter with Team Rocket, she was able to bring out her Venonat's full potential and defeat them. She then returned to the dojo to fully master Pokémon Jujitsu. Pokémon Bulbapedia
Lara and her family own the Laramie Ranch, an area just outside of the Kanto Safari Zone. Lara and her Ponyta and Growlithe helps guard the ranch from Pokémon poachers. Lara was going to enter a race with her Ponyta when Team Rocket, working for Dario, caused an accident that lead to her breaking her arm. Lara was saddened, but quickly realized that Ash could ride her Ponyta in the race. Ash and Ponyta entered the race, and they were able to successfully defeat Dario, and all the other trainers, and win the race. In the process, Lara's Ponyta evolved into a Rapidash. Bulbapedia
Daisuke is a young boy who likes strong Pokémon. He was the original owner of Ash's Charmander.