Where is Looker the agent?

he only is in Pokemon platinum and Pokemon black and white

in Pokemon platinum you see him in jubilife city, and I think maybe at

Team Galactic HQ.

in Pokemon black and white after you beat the elite four, he is looking

for the seven sages. after you find all seven sages he'll

talk to you and he'll arrest the 7 sages. you will never see him again after that.