Super Mario Sunshine Walkthrough
Pinna Park
Episode 7: Shadow Mario in the Park

This is a chase-in-a-loop mission. It's actually REALLY easy because he just runs loop around from fountain. In fact if you get on the other side of him he'll reverse direction, so by going around from side to side you can trap him on the beach by the trees. Hit him TONS of times to get a shine!

Super Mario Sunshine Walkthrough