Hear me out. You can get a Manaphy egg right after second gym, but time starts at the beginning of the game as usual, you can get Jirachi and Mew in Floaroma town, Spititomb is a... possible pokemon, the box legendary is obviously obtainable but the legendary lake trio and others can't be gotten before post game BUT that is still 5 Pokemon you can use in the speedrun, not including your starter at the beginning of the game. Time would be RTA, no cheats(obviously) or glitches(also fairly obviously), time would begin as normal, confirming language and time ends as usual, on the first full black frame before the credits roll. Any thoughts?

As far as I know this has been done already. Also afaik at least Azelf can be obtained before the 8th gym and people have actually considered using it for the main speedrun.