It all depends on what media you're looking at. Lore wise it's him but in a competitive standpoint there's some paradox mons that cancel him with little effort.
Shiny's are just to flex honestly. I don't see how some people have the patience to commit all this time into shiny hunting. Thankfully it gets a little easier with each new generation. All of mine were just dumb luck.
I watched some before that arc because there wasn't a good filler list online at the time. G8 was the only one that fooled me into thinking it wasn't filler until I only had 2 or 3 episodes left.
Not counting the static Gyarados from gen 2. Pretty sure these are the only ones I found since I've been playing since I was around 7/8 years old.
First was a shiny Igglybuff in Crystal from the daycare egg. Didn't know it was shiny because I was young as shit and didn't really use the...