Nintendo Map:
At the Design Maps/Map or CO screen, highlight Map and hold A + L + R. The screen will go blank, then the Nintendo map will appear.

See AW2 Pictures:
At the Sound screen, press Select to check out game pictures.

Adder:
Beat all Black Hole campaign levels.

Colin:
Buy Grit or Olaf at the store.

Drake:
Beat all Green Earth campaign levels.

Eagle:
Beat all Green Earth campaign levels.

Flak:
Buy Flak in Battle Maps.

Grit:
Beat all Blue Moon campaign levels.

Hachi:
Beat all Hard mode campaign levels, or buy everything in the store.

Hawke:
Beat all Black Hole campaign levels.

Jess:
Buy Drake or Eagle at the store.

Kanbei:
Beat all Yellow Comet campaign levels.

Lash:
Beat all Black Hole campaign levels.

Nell:
Beat all campaign levels.

Olaf:
Beat all Blue Moon campaign levels.

Sensei:
Buy Kanbei or Sonja at the store.

Sonja:
Beat all Yellow Comet campaign levels.

Sturm:
Get an "S" rank overall in the campaign.

Thanks to Revolution readers Josh Ustead, Markish, rufus33 and joybuzz!