Okay, so the Poke Radar can be used anywhere except the Friend Safari (at least, Bulbapedia seems to suggest so; I don't actually have XY). Given this, the following Pokémon are still available:
Mareep can be found in a Horde on Route 12 (don't know if Hordes are compatible with Poke Radar, but even if they're not, 5 Pokémon per encounter is great for shiny hunting),
Solosis can be found in Reflection Cave,
Honedge can be found on Route 6,
and Snover can be found on Route 17.
Squirtle cannot be found in the wild, while Magmar and Camerupt can only be found in the Friend Safari (which has an increased shiny chance anyway, so...).