

You can play these online with three other trainers, or alone with three NPCs. Go to one of these to find a big crystal, the chance to do a Raid Battle with a Pokemon of that Tera Type (the actual Pokemon is random).

While exploring, you'll see pillars of light, and symbols on your map that represent certain Pokemon types - Fire, Water, Grass, and so on. You'll have to reduce their health to red to break the Terastallization and be able to catch them (careful not to wipe them out completely!), but once their form breaks, you can try to catch them as normal. These Pokemon are automatically Terastallized when the battle starts, and usually with a random, unconventional Tera type (i.e., a Poison Psyduck or a Fire Diglett).

Wild Pokemon usually can't Terastallize themselves without a trainer, but every now and then you'll see glowing gold Pokemon in the wild. However, there are chances to catch Pokemon with unique or strange Tera types that don't match their regular ones.
