After beating a total of 16 bosses, comprising Club Masters and Team Great Rocket bosses, you face the original four Grand Masters and then two more mini-bosses until you come up to King Biruritchi himself where you have a best-of-three match
Gideon is magically invulnerable, physically fit, chosen by the Gatewatch to strike down Bolas, and so charismatic that Ral Zarek fawns over him two minutes after meeting the guy (more on Ral himself later)
Only a single word was changed, but its an important change: it means you can banish your own character if you want to
Pitch Black is built around Mega Darkrai ex, with Mega Zeraora ex, Mega Chandelure ex, and Mega Excadrill ex also joining the expansion
Even That Grass Looks Greener had to be banned since players would run 60-card decks In the hopes of sending 20 cards to the graveyard