battle tent start and create frontier struct in saveblock

src/battle_controller_link_opponent.c

@@ -1854,7 +1854,7 @@ static void LinkOpponentHandleCmd55(void)
     else
         gBattleOutcome = gBattleBufferA[gActiveBattler][1] ^ B_OUTCOME_DREW;
 
-    gSaveBlock2Ptr->field_CA9_b = gBattleBufferA[gActiveBattler][2];
+    gSaveBlock2Ptr->frontier.field_CA9_b = gBattleBufferA[gActiveBattler][2];
     FadeOutMapMusic(5);
     BeginFastPaletteFade(3);
     LinkOpponentBufferExecCompleted();