The answers to the graveyard are more prevalent in Frontier, but they aren’t anything to write home about. Who wants to play Tormod’s Crypt, anyway?
This means that the decks capable of pulling off graveyard shenanigans are mostly free to run wild. Standard Zombies ports perfectly well to the Frontier format.
Like Standard, everything starts with Prized Amalgam being able to return from the graveyard for free. The best way to turn that on is with Haunted Dead. Both of these creatures prefer to be in the graveyard more than any other zone, outside of actually being in play. If you’re able to get them into the graveyard, they’re sure to be in play in short order anyway.
There are tons of ways to fuel your graveyard in this format. Minister of Inquiries can start loading up your 'yard early, and Cathartic Reunion will make sure that any copies in your hand are put where they’re wanted while digging deep for whatever you need to find.
The biggest addition is Jace, Vryn’s Prodigy. No longer do you need to rely on having another creature in play for Smuggler’s Copter to get a loot ability. Jace does exactly what a graveyard deck wants, and it can even flash back a powerful spell when the time comes. With access to that effect, Collective Brutality goes up in value. This is useful mainly as a removal spell or discard spell, but the reach comes in handy every now and then. Getting cards into the graveyard where you want them with the escalate is a huge bonus.
Kozilek’s Return is another spell that wants to be in the graveyard more than it wants to be cast. It can help you keep the board under control, especially in games where your creatures will be coming back or flipping into planeswalkers. Elder Deep-Fiend is how you trigger the flashback on Kozilek's Return, and generally how you win the game. Sweeping their board while tapping down their lands and sacrificing a creature that will just return from the graveyard is a crushing sequence.
If loading up your graveyard with Ministers, Jace, Haunted Deads, Brutalities, and Cathartic Reunions wasn’t enough, Frontier offers the ridiculously overpowered delve mechanic. There’s a full play set of Treasure Cruises here to reward you for making sure your graveyard stays stocked. Digging through your deck can’t get a bigger reward than Ancestral Recall! Throw in Murderous Cut for some removal on the cheap, and Grixis Zombies is an awesome deck to exploit the Frontier format!