Everyone's image songs are in my musical image song playlist.
Shadow on my sweet memories and I Miss you aren't really Usagi/Moon character/image songs as they are more duets.
Sailor Moon - The Last change, Moonlight Justice (a battle song for Moon/Tux with the Outers as like backup vocals)
Sailor Mars - Honoo no Messenger
Sailor Jupiter - Zigzag Slash
Sailor Mercury - Drive Me The Mercury
Sailor Venus - Traditional The Grace ~Ai no Arashi~
Sailor Pluto - Stay Alone, Forbidden Hades
Sailor Saturn - To A Brand-new World, The World Died Out
Sailor Neptune/Uranus - Choubi! Uranus to Neptune, Harsh! Saint Cry!!
ChibiUsa/Sailor Chibi Moon - Mata Mata Chibi-Usa Desu, Pinky Typhoon
Chibi Chibi/Sailor Chibi Chibi Moon - Mou Ii No
Samael Quartet/Sailor Quartet - Yumeyume Utagau Koto Nakare
Tuxedo Mask - Tuxedo Royale, Miracle Twister
Three Lights/Sailor Starlights - Chasin' After You
Princess Kakyuu - Teikou no Hana (This song is not on an album, it is from the Kakyuu-Ouhi Kourin, which is a sequel to Starlights Ryuusei densetsu, but also sort of its kaiteiban(very sort of...). You can get this song via the live version downloads on seramyuantics.net)
Both for Kakyuu and Three Lights - Kakyuu-Ouhi to Three Lights
Also "Millenium ~ Koi no Senshi Ja Irarenai" (and the 21st century ver.) is like an image song for all the Sailor Soldiers (excluding ChibiMoon since she's not around in the song).