Cactus Makes Perfect Achievement in Forza Horizon 5

The most annoying part of this is waiting until Mexico's wet season. When it's rainy season though, head to the area just to the east of the desert (the Dunas Blancas) and then just head off-road and smash a lot of cacti. 500, in fact. It won't take you long, to be fair, as there are tons around there, so fear not. Just keep an eye on when it's rainy season and you'll be golden.