Populate - Bant WUG - Possibly with a Wolf and Bird subtheme. Those have been fairly common creature token cards in the last few sets. They also have the potential of reprinting Fable of Wolf and Owl which is a Blue Green card that makes both Wolf and Bird tokens.
Madness - Rakdos BR - I always felt Blue Green Madness or Innistrad madness was very orientated to aggro one on one games. So I will wait to see how they implement it for multiplayer games.
Morph - Temur RUG - Animar reprint in sub-commander?
Samurai Legend please. Possibly in Saskia's four color combination. But Mardu will be fine as well. Give it Bushido as a thematic connection, but make the other ability more geared to being playable with and both outside Samurai tribal as well.
Cards like Erhnam Djinn, Juzám Djinn, Serendib Efreet, Balduvian Horde, Ravenous Giant are behind these days.
Some others coincidentally have Morph like Deathmist Raptor.
Madness - Rakdos BR - I always felt Blue Green Madness or Innistrad madness was very orientated to aggro one on one games. So I will wait to see how they implement it for multiplayer games.
Morph - Temur RUG - Animar reprint in sub-commander?
Flashback - Mardu WBR - Past In Flames? Unburial Rites?
Clone is nice because if someone has the best creature on the board then so do you.
Lightning Mauler
Bloodlust Inciter / Goblin Motivator
Anger
Blink
Felidar Guardian
Ramp
Dragonspeaker Shaman
Dragonlord's Servant
Burnished Hart
Solemn Simulacrum
Lifegain
Bishop of Wings
Pillowfort
Windborn Muse
Baird, Steward of Argive
Michiko Konda, Truth Seeker
Politics
Queen Marchesa
Varchild, Betrayer of Kjeldor
Protection
Giver of Runes
Glory
Evasion
Filth
Reanimation
Doomed Necromancer