>>46061916IoA is designed to be played at your earliest convenience, like as soon as you can enter the wild area
CT is just a legendary catch em all, but you can get mons that appear later in your journey much earlier, like snom if ya wanted
they both scale based on how far you are into the story, post game they're in the 60s and 70s
sad part is they didn't bother trying to write a new script that acknowledges that you're the champ
and they also didn't scale your opponents to actually be a champion worthy threat
so if you want more QOL stuff available from the DLC as well as access to plenty of mons, get the DLC, otherwise you won't need it
