I've said this before, but every Smash Ultimate newcomer so far was majorly represented in Smash 4 (+previous Smash games), excluding the Castlevania duo for obvious reasons:
- All had Wii U trophies (including Ken!)
- All but Ridley had 3DS trophies (as his associated stage was Wii U only)
- All 4 who had existed at the time were Brawl Trophies
- All 3 who had existed at the time were Melee Trophies
- 5/7 were Mii costumes
- 2/7 were Assist Trophies
- Ridley was a boss in Pyrosphere and Brawl's Subspace Emissary
For context, the following Brawl characters were trophies in Melee:
- Meta Knight
- Pit
- Zero Suit Samus (technically "Samus Unmasked")
- Wario
- Squirtle
- Charizard (also a Pokeball Pokemon in previous games)
- King Dedede (also appears as stage background)
- Olimar
- Wolf (technically Wolfen)
Additionally, Diddy was mentioned on Dixie's trophy (plus featured in the DK Rap), while Bulbasaur and Venusaur both have trophies that mention Ivysaur.
...and the following Smash 4 characters were trophies in Brawl or Melee:
- Villager
- Little Mac (Was also a full Assist Trophy)
- Palutena
- Bowser Jr.
- Duck Hunt (Trophy in Melee, Sticker in Brawl)
You will note that exempting third parties and the Miis,
this is every character released at the time of each game's release, except for Wii Fit Trainer and Rosalina who both came out very shortly before Brawl's (delayed) release.
With these very-partial-exceptions, no character who didn't even make Trophy has ever been brought on later as a full character.