In 2v2 games, can teammates show their hands to each other, or is hand information kept private between teammates?

Ruling: Teammates can show their hands to each other at any time in 2v2 games. Players can show any card to any player at any time, and teammates can permanently show their private information to each other.

Nuances:

• Showing cards to another player is different from the "reveal" game mechanic
• When you show a card, it does not count as a "reveal" for game effects that trigger on revealing cards
• Players cannot choose to look at opponents' cards, but you can voluntarily show your cards to anyone