Uhh, this is a tough one :
C64 - Giana Sisters
CPC - Bombjack
SMS - Wonderboy
Mega Drive - Mickey Mouse - Castle of Illusion
SNES - Super Probotector (german Version of Super Contra)
Amiga - Zool as well as Giana Sisters
NES - Mario Bros.
PSX - Pandemonium
PS2 - no Platformer played yet
N64 - Mario 64
MSX - JetSet Willy II
NeoGeo - Magican Lord (this one really ROX !!!)