So I was planning on getting a shiny Sentret in Pokemon X but I fly out there and try to use Pokeradar(not on skates or bike) and I get the "Mom's words echo in your head, ect ect", can I not chain in tall grass?
No, you cannot chain in the taller grasses. It's unfortunate. However, if you really want a shiny Sentret, the Masuda Method is always an option :)
Hope I helped!