From Bulbapedia, the community-driven Pokémon encyclopedia.
Robert's grandfather (Japanese: ロバートの祖父 Robert's grandfather) is a character of the day that appeared during Robert's flashbacks in The Four Seasons of Sawsbuck!.
Like his grandson, he was a Pokémon photographer and had traveled the world taking pictures of Pokémon. Robert showed off his grandfather's collection of photos to Ash and his friends. One of his greatest accomplishments was getting a photo of all four seasonal forms of Sawsbuck in one place. Robert greatly admired his grandfather and his work which motivated him to get his own picture of the four Sawsbuck forms.