>>46559474Gen 5 Pokestar studios experimented with non Pokemon opponents and Raid Battles and Totem Trials are basically boss fights. They've also been trending towards making legendaries easier catch with more forgiving rates, especially for the box legends who are required to advance the plot.
In most RPGs if you fight a character and recruit them to your party, they don't necessarily represent how they would behave once part of your team. Or if they drop a weapon symbolic of that boss. They could just make tough to beat boss versions of Zapdos or Raikou or whoever, have the player fight and defeat them, and then have a brief pause after the fight where the player can save for a soft reset and then catch the legendary. Or they can do it the way they did with Necrozma; defeat the tougher boss version then come back later to add it to your team. idk how it works with Raids exactly because I didn't buy swooshie, though.