how do you find rare pokemon with the pokeradar?

I think the patches of grass that are furthest away tend to be rarer. The more the grass shakes, the more rare it will be.

the more it shakes, or the faster it shakes, or the longer it shakes? Which one?

Uh, I thought the further away they were, the more common they got. Oh well, I'm probably wrong. But definitely, the more the grass shakes or shines, the rarer the Pokemon.

Patches that have a better chance of having a rare pokémon in them have these light green shines on them when they shake. However, rare pokémon may be in any of the patches.

The further away the patch from you, the more likely it'll have a rare pokémon.

This is not always the case though. You may run into a regular pokémon in one of those patches, but not too often.

I've read that the further away patches are more likely to contain whatever pokemon you've just battled.

yeah thats what i heard. the one farthest away is most likely going to be the same poke u just faced

That's what Dawn/Lucas says.

Maybe the furtherest away patch is rarest when you first use the pokéradar each time