I've done some routing on All Diamonds, but the next long-form category I'm looking at is All Research Levels. The main reasons being it's more comfortable routing for me, and because it doesn't need a lot of technical support (you'd need a spreadsheet for All Diamonds)
I have 2 things to note:
Seconding the idea of coming to the discord. I know personally I love talking about the speedrun, perhaps more than actually doing runs. It's a really fun game to route and become an expert in. We'll be happy to talk shop.
Also, I'll note All Pokes is cool. Any% is a more natural starting point, but is a slow game with lots of cutscenes and the Illumina pokes are basically autoscrollers. All Pokes goes through all those same things, but the second half of the run is all boosting and no cutscenes. Percentage wise, more of what makes Pokemon Snap fun happens in the run, so I enjoy it more as a run.
