It’s no secret, Dialga and Palkia will be obtainable in Pokémon Legends: Arceus, both, but not at the same time. In fact, during the last missions of the main campaign, you will be asked whether to be accompanied by Damon or Perula: this choice will affect the order in which you will get the two Pokémon.
- By choosing Irida you will find yourself facing the legendary Palkia in a traditional Pokémon battle (and you can catch it using your Poké Balls), while later you will have to face Dialga Original Form as if it were a royal Pokémon (dodging its attacks and throwing Sferezen at it). The capture of the latter will be ensured by a special Origin Ball at the end of the fight.
- Choosing Damon, vice versa, you will go first to Dialga that you can traditionally capture with your Poké Balls, and then to Palkia Original Form for an action-packed fight with Sferezen shots, with capture ensured by the Origin Ball at the end of the fight.
Congratulations, you have thus obtained the master of Time, Dialga, and that of space, Palkia, in Pokémon Legends: Arceus and you can take them for a walk throughout Hisui in their classic form. Instead, you will have to wait for a few more missions to get the tools necessary to change their shape.