SSB
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Princess Peach
Bowser
Toad
Pit (but was replaced by Jiggypuff)

SSBM
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Princess Peach (finally added to SSBM Roster)
Bowswer (Finally added to SSBM Roster)
Toad (was dropped)
Pit (couldn't added because he was difficult to create with his wings. Also Melee dont have aerial battle)
Diddy (Was dropped due to time restricted)
Wolf (was dropped due to time restricted)
Balloon Fighter (same reason as Pit. It was in Beta Verison)
Wario (was dropped due to time restriction)
Ridley (was dropped due to time restriction)
Snake (was dropped due to time restriction
Sonic (I am not sure if it is true but I heard that Sega did asked but Nintendo told them it was too late)