Ok, so a lot of people don't know this, but if you have the Crown Tundra DLC, then you can go and catch the legendary Pokemon in the Dynamax Adventures immediately. As in, as soon as you get the Dynamax Band. As soon as you talk to Magnolia and fight Hop for the 2nd time, you can go to the Wedgehurst Station, catch the Galarian Slowpoke, and then go to the Crown Tundra. It is not necessary to win against Peony to progress in the story. So as soon as you lose to Peony you can go catch a Lvl. 60 Suicune with your OT so it will listen to you. This is by far the fastest way to progress in the game, as you are able to one-shot everything from the Pokemon in the Wild Area to Leon's team.
Hope I helped!