Leon is an evil villain that saw
Ash's Pikachu and
Meowth as good targets to steal because they were rare in the Isshu region.
Leon's character design is a clear reference to the "mechanic" character from the various
Time Bokan series.
Leon is also quite fluent in French.
Leon is a very eccentric character who borders on megalomania. He taunts its victims and dares them to try to attempt to catch him.
Leon's Beheeyem is used to help him create dream world's and dream world layers which makes it difficult for his victims to figure out exactly what's going on which makes it a lot easier for him to escape.
Unfortunately for
Leon, Psychic type Investigator
Officer Jenny (Unova) had been hot on his tail and was investigating psychic instances and crimes.
Officer Jenny (Unova) and her
Jenny's Duosion helped rescue
Ash's Pikachu,
Meowth and
Iris' Axew from
Leon and arrested him.