Within the Max Liar found in the Crown Tundra, players can participate in what are known as Dynamax Adventures by speaking to the scientist that runs them. Dynamax Adventures sees players having to go through a Pokemon Den full of Dynamaxed Pokemon. Players will get their pick of a Rental Pokemon to begin the Dynamax Adventure, and four trainers must participate in order to do one (whether online with other people in the real world or with NPC Characters the game with generate).
After selecting their Pokemon, players will then have to defeat three straight Dynamaxed Pokemon on their way to battling the Legendary Boss Pokemon. Your entire team of four people will only have a total of four lives to lose during the entire Dynamax Adventure; they do not reset after defeating one of the Dynamaxed Pokemon to the next. Should your team have four Pokemon faints total up at anytime during the pace to defeat four Dynamax Pokemon in a row, you will be kicked out of the Pokemon Den (similar to normal Max Raid Battles).
There are numerous paths apart of a Dynamax Adventure, allowing players to pick which path and Dynamaxed Pokemon to battle. The goal here is to pick the Dynamaxed Pokemon that the Pokemon your team has will fair better against. Along the way through a Pokemon Den, you can find berries to help your Pokemon Team recover HP, scientists that will allow you to switch your Rental Pokemon, and even backpackers that will give your Pokemon battle items. After defeating a Dynamaxed Pokemon, you will have the chance to capture it and replace your Rental Pokemon with it.
The final of the four Dynamaxed Pokemon you will battle will always be a Legendary Pokemon. In total, there are forty-four different Legendary Pokemon that can be found and captured in Dynamaxed Adventures! At the end of your Dynamaxed Adventure, you will be allowed to keep one of the Pokemon you captured during your Dynamaxed Adventure. (Of course, most people select to keep the Legendary Boss Pokemon if caught).
We have questions and answers related to this topic which may also help you: