The Pokémon anime debuted in Japan back in 1997, following the adventures of ten-year-old Ash, Pikachu, and their friends.
However, probably the biggest change was Ash’s eye color back in 2010 when the series Pokémon: Black & White featured Ash with brown eyes instead of black ones.
The character’s eyes (the pupil and the iris shape, really) have changed once again with the most recent anime Pokémon XYZ.
In this summer’s new Pokémon anime feature film, the character’s design has reverted back to a more “traditional” look.