By doing a quick search I was able to track down codes for unlocking enemy range, battle saves, weapon triangle, and map affinity on hard mode. Here's the list:
Enable Enemy Range on Hard Mode
04191AC8 28000003
04052C98 28000003
04067C5C 28000003
Enable Weapon Triangle on Hard Mode
0402A8A8 28000003
Enable Map Affinity on Hard Mode
040F97D0 28000003
04119440 28000003
Enable Battle Save on Hard Mode*
04025DBC 2C000003
0404B664 28000003
04025468 28000003
04025720 28000003
04025814 2C000003
*When you save it works just like a battle save, but when you resume it, it says suspended data and deletes the save after loading it, so you have to re-save if you want to resume again.
This was a godsend for me because I really wanted to see what hard mode was like without "fake difficulty". You'll need Homebrew Channel on your Wii, and Gecko OS.