Pokemon GO Global Catch Challenge begins tomorrow with interesting rewards

Pokemon GO Trainers around the world will be participating in a new Global Catch Challenge where interesting rewards can be had depending on how many Pokemon trainers catch over the next seven days. From November 20th through the 26th, trainers can unlock three tiers of rewards. Catching 500 million Pokemon will unlock the bronze-tier reward and will yield double XP, six hour lures, and increased Pokemon spawn rates (for how long wasn't specified). The silver tier will be unlocked at 1.5 billion Pokemon and will include the bronze tier rewards and double stardust. Finally is the gold tier which will yield not only the bronze and silver tier rewards, but will also make Farfetch'd available worldwide and Kangaskhan available in east-Asia, each for 48 hours. In other words, help trainers catch a ton of Pokemon so we can finally get another regional Pokemon that doesn't require us to travel to another continent.

UPDATE: Originally forgot to put that Farfetch'd and Kangaskhan would be available for 48 hours.  Also recently saw via the Pokemon GO Facebook page that the Bronze and Silver tier rewards would last until December 1st at 1:00 p.m. PST.