Pokémon Platinum for the Nintendo DS was James' 12th Let's Play. The series ran from January 1st, 2016 to June 3rd, 2016.
You can watch the series from the beginning by clicking here.
"The first (and only) Pokémon LP to be a 3rd installment of the core series!"
- The series icon featured above was created to match the current "JR" design, as with every series prior to Kirby: Planet Robobot