Mechanically speaking, why does the Soul Dew exist? In fan-made rulesets like Smogon, it used to be banned because the Latis were busted with such huge boosts to their Special Attack and Special Defense, but this isn't something that Game Freak thought was balanced and then banned by fans. No, Game Freak knew
that this item was busted. In official rulesets (both single and multiplayer)
where restricted legendaries like Mewtwo and Kyogre are banned, Soul Dew is also banned, or disabled in the case of Gens 3 and 4 battle facilities. Game Freak had been making trios of unrestricted legendaries since Gen 1. Hell, they made another trio of unrestricted legendaries in Gen 3. But when it came to designing the first unrestricted legendary duo
, Game Freak decided to also give them a held item that turned them into restricted legendaries because... why? What was the thought process behind intentionally giving them an item that makes them Mewtwo tier? What was the thought process behind intentionally forcing every game until Sun and Moon to muddy its official banlist with this one single
item. Because again, it was intentionally
busted. From its very conception, this held item was treated the same as whole restricted Pokemon by Game Freak themselves.