If Thalia enters the battlefield at the same time as an opponent’s creatures or nonbasic lands, those creatures and lands aren’t affected by Thalia’s last ability.

If an effect states that a creature or land enters the battlefield tapped unless a condition is met, Thalia’s last ability has it enter tapped even if that condition is true. For example, your opponent may reveal a Plains while playing Port Town (from the Shadows over Innistrad set), but Port Town will still enter tapped.