>>46801582OHKO moves are uncompetitive garbage that should not be part of the game. As for everything else, the issue is that most of those or so good that they warp the meta so they have to be moved up to Ubers. Even if Ubers is a banlist it's 100% playable so if you want to use most of the stuff you lists, just play Ubers.
Beside that, there are VGC and BSS formats on Showdown that follow the EXACT rules Game Freak provides. Even ignoring that, there is literally a format called Anything Goes that lets players do whatever Game Freak allows on cartridge, with the sole exception being causing an endless battle (ironically meaning that the only thing Smogon doesn't let you do, is Stall forever).
Finally, Game Freak either doesn't know now to balance the game or (more likely) actively goes out of its way to make the make unbalanced. Zard and Typhlo were pretty much equals (as they should be) until Lame Freak started paying attention to the meta and fucking everything up, now Charizard is broken in VGC and Typhlosion is "do not ever use this Pokemon with the intent of winning games"