I don’t really get it, how do you see if a Pokémon has a mark, and do they have any effect on the Pokémon?
Marks are essentially just Ribbons except that a Pokémon can only have one Mark, at it is obtained when the Pokémon is caught. Also, Pokémon have a 5% chance to have a mark. You are that the Pokémon has a mark in the Summary Page. Then Marks have no effect on Pokemon except the mark gives it a title when it is sent out to battle.