The Pioneer Azorius is one of the preferred MTG decks in the format if you are going with some tempo-style deck strategy that caters to cheap, flashy creatures and counterspells that prevent opponents from developing their board. That is also my personal choice of gameplay.

Creating a sideboard plan for an Azorius Spirits Aggro deck in Pioneer involves preparing for a variety of matchups and adapting to the metagame. Here’s a sample sideboard plan that you can use as a starting point.

Keep in mind that you may need to adjust it based on your local metagame and personal preferences.

Against Aggro Decks (e.g., Mono-Red Aggro, Humans, Mono Black Aggro):

2-3 Portable Hole – Fend off the early aggressive aggro curve. 

1 Rest in Peace: To shut down graveyard-based strategies and recurring creatures. 

Skyclave Apparition – A creature that can exile an opponent’s creatures while also providing a good blocker. 

Spell Queller: For additional counterspells and creature flying threat.

Extraction Specialist – three-drop lifelinker that can also return your creature card that has died in the early turns. 

Against Midrange Decks (e.g., Gruul Aggro, Selesnya Angels)
Disdainful Stroke – To counter relevant midgame spells and creatures.

Destroy Evil – Utility Spell to kill large toughness creatures and enchantments such as Fable of the Mirror Breaker

Wedding Announcement – Develop the board with Human tokens while also providing an anthem effect.

Settle the Wreckage: For mass removal against a situational creature-heavy opening.

Against Control Decks (e.g., Azorius Control, Lotus Field, Esper Control):

MD Spell Queller: To apply pressure and counter their key spells.

2-3 Mystical Dispute – To counter their counterspells, Teferi, and card draw.

Tocasia’s Welcome – Provide card draw gas midgame to late game.

2 Remorseful Cleric – A spirit that can disrupt their graveyard-based strategies.

Remember, sideboarding is highly dependent on the specific decks you expect to face in your local metagame. Always pay attention to the evolving metagame and adapt your sideboard plan accordingly. Additionally, practice and experience will help you fine-tune your sideboarding choices for Azorius Spirits in Pioneer.