Smogon Stats Parser
Run the program by running tiershiftanalysis.py in a Python interpreter. Requires matplotlib, sklearn and pandas. First, though, you need the data.
Data is not included because github would get very mad at me if I put all of that here.
Go to https://www.smogon.com/stats/ and download gen8-ou-1695.txt and gen8-uu-1630.txt from all folders between 2020-12-H2 and 2022-06.
Then put them in the stats folder, in folders with the same name. You can also use the httrack website copier program to retrieve even more data.