Sideboard Theory:

>Nykthos Ramp

In: 3x Inscription of Abundance, 2x Vivien, Arkbow Ranger.
Out: 3x Werewolf Pack Leader, 2x Cemetery Prowler.

Inscription and Vivien come in to help buff our creatures.
We want every creature to be able to trade with their inevitable Old-Growth Troll, so Werewolf Pack Leader is out as a 3/3.
Cemetery Prowler isn't too useful apart from exiling Storm the Festival, so both come out.

>Rakdos Midrange:

In: 3x Blossoming Defense.
Out: 1x Old-Growth Troll, 1x Steel-Leaf Champion, 1x Aspect of Hydra

Blossoming Defense can blank removal and work as a combat trick situationally.
Just trimming cards here, most are useful in the matchup.

>Izzet Phoenix:

In: 4x Scavenging Ooze
Out: 4x Lovestruck Beast

Ooze can exile their Phoenixes and Galvanic Iterations while being a threat.
Phoenix has too many ways to burn down the 1/1s for Beast to be consistently attacking, it's not even useful as a blocker as all their creatures fly.

>Abzan Greasefang:

In: 4x Scavenging Ooze.
Out: 1x Lovestruck Beast, 1x Steel Leaf Champion, 1x Werewolf Pack Leader, 1x Yorvo, Lord of Garenbrig.

Ooze and Cemetery Prowler hopefully help us avoid a turn 3 Parhelion II.
Trimming cards to add in more focused answers.
The goal here is to disrupt their early combo attempts, then finish them off before they stabilise

>Azorius Control:

In: 3x Prowling Serpopard.
Out: 2x Cemetery Prowler, Yorvo, Lord of Garenbrig.

Serpopard can't be countered and gives that ability to the rest of our creatures, which is very useful for starting to set up a board.
Graveyard hate isn't super useful, so the Prowlers come out. Yorvo is the worst of the three drops in this matchup, so he comes out.
The game comes down to choosing the correct time to CoCo and out-pacing them.

>Mono-White Humans:

In: 3x Inscription of Abundance.
Out: 2x Cemetary Prowler, 1x Rhonas the Indomitable.

Using Inscriptions to fight Brutal Cathar and Containment Priest is the way to go here, just keep up pressure and force them to sacrifice their creatures to block.
Graveyard hate is less important so the Prowlers come out, Rhonas out as most of their removal is exile based.