Doctor Kodama

Professor Kodama is a character of the day who appeared in Sticking With Who You Know!.

Kodama had created a machine, called the "Affinity Enabler", that made Electric-type Pokémon and Water-type Pokémon become inseparable. He created it with the intention of making Pokémon who do not get along become closer to each other. Two of the Pokémon affected by his machine were Ash's Pikachu and Dawn's Piplup. However, his Quagsire and Magnemite seemed to despise each other even when the machine was turned on.

He had hired Team Rocket as his assistants. They eventually decided to steal the machine, along with Pikachu and Piplup. However, Kodama had also been captured by mistake, which led to Quagsire and Magnemite joining forces in order to rescue him.

Brock explained to Professor Kodama that perhaps the machine did not work on Magnemite and Quagsire because they were dual-type Pokémon, with Quagsire's secondary type being Ground and Magnemite's secondary type being Steel.

(Source: Bulbapedia)