You could actually catch multiple of the team leader Pokemon with just one radar every hourly similar to the multiple shadow moltres glitch until 10pm that is.
The shadow Pokemon iv is rerolled every hour and the trigger for the reroll is either encounter any wild Pokemon spawn or redeem any of the reward Pokemon stack.
The mechanics works like this... After defeating any of the rocket leader or Giovanni, feed any berry to the shadow Pokemon but don't catch it and run away while taking note of the time. It's crucial to note the exact time because you cannot catch any Pokemon after 1 hour from the shadow Pokemon encounter. Within the hour you can play freely.
When the hour mark from the shadow Pokemon is up, go to the pokestop and encounter the shadow Pokemon again. Feed it a berry and it should be rejected because this is the first instance which you have fed a berry an hour ago. Use the quick catch method to catch it. Then click on the pokestop and you will get the rerolled shadow Pokemon. At this point, you can either feed another berry and note the time and rinse and repeat one hour later or just catch the second instance and be done with it.
The rational for feeding the berry is to let you know if the encounter is the previous instance or the rerolled one. If you happened to triggered the reroll because you forgot and caught a Pokemon after the one hour mark, you will have to wait for the following hour and not catch it as doing so will stop the reroll process.
In any case, shadow Pokemon can't be traded so guess it's only useful if you are rerolling for shiny or trying to farm candy.