Maybe this is a joke, you never know with Pokémon discourse, but it's completely inaccurate. If you think the PS1 was able to run a game that looks anything like Pokemon XY, I think you should play a PS1 game to refresh your memory.
I'd argue of all the Pokémon games, the only one that looked bad for the time and hardware it came out for was SwSh, and even that isn't nearly as horrid as people make it up to be, it looks like it was rushed and completely skipped polishing, but the artstyle is great and it can look quite pretty sometimes. It looks nothing like a PS2 game.
Gen 9 looks exactly how I expect an open world game with tons of models in the field that isn't made by an internal Nintendo studio to look on the Switch. Yes, GF has a problem with textures and lighting, but overall the game looks great, I dare you to find an open world game on the Switch that looks better and isn't called Zelda. Performance is a disaster of course, but it's also expected when a game of that scope was made in three years.