The Tapu(s) are legendaries, not pseudo Legendaries. And the asker only wanted to know about unobtainable shiny legends, not mythicals too. Marshadow and Zeraora are unobtainable in all ways because their events are over so they shouldn't be in this answer. Tapu Koko should be added to this answer because it's shiny was an event that's now over. Also make sure Tapu Lele stays in this answer because it's an event too.