Daily Quests can be made every day, with rewards in Experience points and Tokens. The NPCs who provide these quests are located in TC (Trade Center) and change their challenges every day.
NPC Leiko: Begginer Level.
NPC Miyuki: Easy Level.
NPC Amaya: Average Level.
NPC Junko: Hard Level.
To start that quest, start talking 'hi', then accept it with a 'yes' and then say the Pokémon name and confirm with a 'yes'.