Lucky Pokémon, Pokémon GO Wiki
Serebii updated Level 50 Challenge for part 3 (new info?) : r/TheSilphRoad
The Silph Road
Pokemon GO Level 50 Rewards: Research Task Level Bonkers - SlashGear
Catching Pokémon, Pokémon GO Wiki
Level 43, 45, 48 and 50 Challenges Tasks and Rewards
Level 45 Challenge : r/TheSilphRoad
Pokémon Go Power up PokéStops: How to power up PokéStops or Gyms explained
Level 50 Challenge, Pokémon GO Wiki
Pokémon Go Showcase, including how to enter PokéStop Showcases, how to switch Pokémon and rewards explained