Dragon/Ghost based on the Dragon Dance in the Chinese New Year (http://i45.tinypic.com/qr0qdj.jpg).
>Scary/angry look
>Not legendary
>High Spe/SpA, medium Atk/SpD, low HP/Def
>First evolution = small, floating, baby Dragon mask
>Second evolution = medium mask, short/stubby body
>Third evolution = large mask, very long ethereal body

Grass/Ghost based on a Weeping Willow (http://i45.tinypic.com/t8m3vb.jpg).
>High HP/SpD, medium Atk/Def/SpA, low Spe
>Old/sad look

Steel/Ghost based on a floating/possessed suit of armor (http://i50.tinypic.com/2v8h6x1.jpg)
>Calm/emotionless look, no face
>High Atk/Def, medium SpD/HP/Spe, low SpA
>Pre-evolution could be a floating shield or something

Ghost/Fighting based on a floating/possessed training dummy (http://i50.tinypic.com/32zib1x.png).
>High HP/Def, medium Spe/SpD, low Atk/SpA
>Goofy/silly look

Ghost/Rock based on an ornate, ancient urn that collects spirits (http://i45.tinypic.com/1z1g3uw.jpg).
>Emotionless, no face
>Lid off with spirits/ethereal "mist" pouring out
>High SpA/Def, medium Atk, low SpD/Spe/HP

Alternatives for trade evolutions.
>Never going to happen