You seem to be refusing to accept the idea both of those are false the player character likely has the legendary and can use it battle second how can they indirectly have this level of power. Honestly this seems to be an argument from incredulity.
No, i don't think its likely (and even if its likely, its not confirmed so its a bare assumption) that the player character 'canonically' used their Space/Time God in a sparring/friendly match just because you have the choice to use the legendary as a player choice.
Ppl taking whole ass separate playthroughs as canon instead of trying stick to the what the storyline is the same as is the weird part. Whats so special about the player character if anyone in Galaxy Team can just 'take on Tier 2 level pokemon'. Why are they the only ones capable of saving everyone?
It's just backwards scaling that holds no ground other than the reliance of game mechanics, in that NPCs you fight have the capability to injure your pokemon. So do random Wild pokemon. We shouldn't be relying on that when we're talking abt separate individual playthroughs, cause then you can get stuff like Kricketot being Tier 2 which is just openly insane.
Yeah, the protag canonically 'fights' the Legendaries (or at least just...throws some calming balms at them) so they're fine to scale. Not every RPG narrative wise is then gonna have anyone that you can openly battle if you choose to, based on a game-levelling system thats never properly canonized as an actual thing, scale to the literal Creator of the Universe or smthn.
If you include Rei and Akira in Galaxy Team then sure, but the page openly does not include them for whatever reason, despite literally being the MVP. Literally, even Volo can scale to Tier 2 sure, but literally any character for having a post-game team that you can choose to fight should not be considered.
Plus its never a point that Rei/Akira had actually, canonically struggled beating any of them while using a legendary either. Like its just very weird scaling to put literally the NPC randoms you can choose to have a battle with scaled to the literal Gods they were worshipping and reliant on YOU to defeat.