Trade data; split off trade_scene

include/trade.h

@@ -1,6 +1,11 @@
 #ifndef GUARD_TRADE_H
 #define GUARD_TRADE_H
 
+extern struct MailStruct gLinkPartnerMail[6];
+extern u8 gSelectedTradeMonPositions[2];
+
+extern const u16 gUnknown_826601C[];
+void sub_804C718(void);
 s32 sub_804FB34(void);
 
 #endif //GUARD_TRADE_H