If an attacking creature has forestwalk and the defending team controls a Forest, what can happen?

When a creature has forestwalk, it means that it cannot be blocked by creatures unless the defending player controls a Forest. In the scenario you’ve described, the attacking creature possesses forestwalk, and the defending team does indeed control a Forest. Given this situation, the attacking creature is considered unblockable due to the effect of its ability. As a result, no creatures can block the attacking creature, making it successfully evade any blockers.

This aspect of the game emphasizes how abilities like forestwalk interact with the types of lands controlled by the opposing player, highlighting the importance of land types in combat interactions. Other choices may suggest situations where blocking could occur, but the specific ability of forestwalk unequivocally prevents blocks when the condition is met.