Brawl has true combos for every character I believe, most at low percent. At low percents Olimar can go Dthrow > Usmash (< Usmash percent was low enough from the Dthrow) or Usmash > Usmash (>Usmash again if low enough) as long as a purple doesn't get in the way. Lucario has a lot of shenanigans with Uthrow, Utilt, and Fair and can go to relatively high percents with combos. Toon Link has Bair > Bair > Bair. Marth has grab stuff. Chain Grabs can be consider as combos as well to a degree. Ect...
They're few and mostly at low percents but they do exist.