It doesn't have any inherent rules meaning, but some Gates, including some found in this set, have abilities that care either about which other Gates you control or the number of other Gates you control
Opening a god pack, with all ultra-rare cards, is extremely rare but possible
You could also go with a long term plan model: Test of Patience R Sorcery (R) Search your library for a card, shuffle your library, then shuffle that card into the top three cards of your library
I started collecting Pikachu cards exactly a year ago (October 2015), and when I saw the Bulbapedia list I was already suprised to see so many cool cards I had never seen before
The rarity is also printed as a letter following the card's set number, at the bottom of the card
If a battle that's being attacked somehow stops being a battle, it is removed from combat