Would my effects cover my partner's GY as well as mine in a Tag Duel?
Basically, if you and your tag partner both use Dragon Decks, would their effects cover your partner's GY as well?


From the wiki page on Tag Team Duels we have, emphasis mine:


  When taking part in a Tag-Team Duel, both teams consist of 2 players. Players share a combined Life Point total and their fields and Graveyards.


So yes, you and your partner share graveyards.

Here's also a link to the Official Tag Duel Rulings, for reference.