Ash, Misty, and Tracey are walking through an old town. They comment on how quaint it seems, and Misty says that it reminds her of "Merry Olde England." They see a girl running towards them, shouting the name, "Maria." She stops and asks them if they've seen Maria. When she realizes that they are visitors, she tells them that Maria is her Nidoran. She explains what she looks like, and Ash looks in his Pokédex. The display shows a Male Nidoran, and the girl tells him that Maria is a Female Nidoran. Ash switches the display, and the Pokédex shows the correct picture. Ash offers to help the girl find Nidoran.
Their search takes them to a park, where they walk around, calling out Maria's name. Ash sees a boy running around, calling out a different name: Tony. He runs up to him and Misty and explains that Tony is a Nidoran and he's been running away a lot. Ash looks in his Pokédex again, and the display shows the Female Nidoran. Ash switches it to the Male Nidoran, and Tracey and the girl run up. The boy pushes Ash out of the way and he and the girl start to yell at each other, accusing the other of stealing their Nidoran. They pick up some sticks and start fighting.
Marill walks up to Tracey, and he asks it if it has found anything. The boy and girl run off, trampling Tracey in the process. They find their Nidorans sitting among some rose bushes. The pinkish Nidoran (Tony) picks a rose and gives it to the whitish Nidoran (Maria). As Tracey sketches the couple, Misty comments that the two Pokémon appear to be in love. The boy and girl scoop up their Pokémon and carry them off in opposite directions. The Nidorans look at each other, sadness in their eyes.
Later, Ash and his friends stop in a diner for some lunch, and the chef tells them that the two kids he met are named Ralph and Emily (I'll let you guess which is which). He explains that they have known each other since they were really young. They have always been very competitive with each other, and have always somehow managed to capture the exact same Pokémon. Whenever Pokémon contests were held in town, Ralph and Emily ended up tying with each other. The most recent one had them both win. They were unhappy with this, but their Nidoran were quite fine with it. The chef finishes the story, saying that it is just too bad for them. That evening, as Ash and his friends walk through town, Tony runs across their path. They follow him until he stops in front of a house. Maria comes out onto a balcony, and they call to each other. Misty tells Ash that they are talking sweet talk, and teases him about being rather immature. He feels very insulted. Suddenly, Emily comes out onto the balcony behind Maria and pours a bucket of water all over Tony. Ralph runs over, picks Tony up, and carries him to their house; which, surprisingly, is right next door. Misty decides out loud to do something about all of this, despite Ash's comment that it's none of their business. She calls him a baby again, and he once more is insulted.
Meanwhile, Team Rocket watches from the bushes. Meowth tells them that they could steal the Nidoran, wrap them up, and give it to the boss as a present. They continue to plan. Later that night, Misty sits writing at a desk in their room at the Pokémon Center. Ash asks her what she's doing, and she tells him that she's writing identical love letters to Emily and Ralph in order to get them together. She says that they like each other, but just aren't "mature enough" to admit it. Tracey notes that it's the exact same scenario with Ash and Misty, and they attack him.
Back at Ralph and Emily's houses, Jessie explains to James and Meowth that they need to convince Tony and Maria that they need to come with Team Rocket to be together. She goes into a memory sequence, thinking back to some of the loves she has lost. James and Meowth try to comfort her, but only insult him. She tells Meowth to go. He crawls up to Emily's room first, and asks Maria if she wants to be with Tony forever. He goes to Ralph's window and asks Tony the same thing. He comes back to Jessie and James empty-handed handed, however, saying that neither Nidoran wanted to disobey its master. Jessie gets ticked off, and tells them that they need to go to plan two: Nidoran-napping. The next day, Ash and his friends hide behind a tree near where Misty had told Emily and Ralph to meet. She tells Ash and Tracey that, along with the notes, she sent Emily a bouquet of flowers and Ralph a toy airplane. Just then, both kids show up on the scene. Unfortunately for Misty, they seem to hate each other even more. Apparently, Emily is allergic to flowers and Ralph gets air sick really easily. They yell at each other some more, and start to fight with sticks again.
Suddenly, they all hear some church bells and see a bride and groom approaching. They all congratulate the couple, who say a little poem and grab the Nidorans. As a huge, fake wedding cake rises up underneath them, they tear off their costumes. Surprise! It's Team Rocket (wait, why was James dressed as the bride? Must be to help with the disguise). The cake splits, and the Meowth balloon rises up. Jessie and James jump in, still holding the Nidorans. They fly off, with everybody staring at them.
Ash and Tracey start to run after Team Rocket, and Misty yells at Ralph and Emily for fighting with each other. She turns and smacks into Ash and Tracey, who are standing still and staring at the ground. The cans that were attached to the balloon have fallen off, forming an easy to follow trail.
Once Team Rocket have landed, Jessie and James struggle with Tony and Maria, trying to get them into little costumes. Ash and his friends show up and tell Team Rocket that they should've been a bit more careful. Maria and Tony start to run to their masters, but Arbok lunges at them. Both Pokémon, under their masters' commands, Tackle the huge snake, who flies backward. James sends out Victreebel, but this move is futile, since it eats Jessie. Maria Scratches Victreebel, and Tony is Tackled by Arbok. Maria goes over to see if he is ok, and he pushes her out of the path of a Tackle from Victreebel. Maria Tackles Victreebel, and Tony Scratches Arbok, while Ash and his friends look on. Tracey comments that they really know how to battle. Victreebel lands on Tony, but a Tackle from Maria sends it flying off. Ralph and Emily realize that their Nidorans are fighting for each other. Arbok catches both in its coils, but lets them go after they bite it. They Scratch Arbok and Victreebel, then Tackle them. Emily and Ralph command Fury Swipes, then blush as they catch each other's eye. Then the two Nidorans serve up a double dose of Double Kick, and both of Team Rocket's Pokémon are vanquished.
Team Rocket jumps into their balloon, and Meowth starts up a vacuum. Pikachu jumps up and shocks them, however, and Misty's Staryu pops the balloon. Misty yells at them to not mess with Pokémon in love, then turns to Ralph and Maria. She tells them that they really should let their Nidorans be together. They don't want to give them up, however, but Tracey has an idea. He tells them that they can build a little house for Maria and Tony, and they blush. Misty tells Maria and Tony that now they'll be able to be together and they kiss. Suddenly, they both start to glow and evolve into Nidorina and Nidorino. Tracey draws in his notebook and wonders how they evolved: "from the battle or the kiss". Misty, blushing furiously, hits him and Ash asks her if people change when they get kissed. Still blushing, she responds, "Guess we'll have to find out ourselves".
Ash and his friends wave farewell to Emily and Ralph and their new Pokémon.