So let me see if I've got this.
Marsh grabs all of the Balls with the main legends in them and starts running, MC gives chase and she starts asking questions on the Legends, maybe each one the MC gets right, she throws the Ball back to him?
There's extra questions for the Gen 7 Legends if they've been caught already.
If you get them all then she stops running and gives you your reward, I guess if you fail she tosses all the Balls at once and disappears into the shadows