I_AmNoJedi on reddit made a watch/read list for people to get up to speed for the Ahsoka series! Hope this is helpful:
Oof, that is a rough list. It’s far too cut down in my opinion but it’ll get the job done for those that are absolutely rushed. And I’m honestly a little horrified that they’d recommend watching Practice Makes Perfect before the series. TOTJ should only be watched after one has seen the series proper. Also not a fan of giving one of the arcs a custom title that is very spoilerific.
A while back I created an essential Clone Wars watchlist for a friend who wanted to get his girlfriend into the show but didn’t want to get bogged down in the lighter episodes of the series. It turned out to be a huge success and I’ve continued to refine it, taking into account required viewing for later series like Mando and Bad Batch.
With so little time until AHSOKA begins airing it’s not the most expedient to get through before then. But I’d say it’s the more holistic route to appreciate the series as a whole and the connections that have sprouted from it to a lot of the current Star Wars storytelling.
So here’s my list for anyone that might be interested:
The episodes are listed in chronological order with one exception and are listed with a three digit code where the first digit is the season number and the following two are the episode number. While not essential I’ve also included the Genndy Clone Wars mini-series as a solid lead in to the era and a plug for some holes left open by the series that followed it. But it’s entirely optional.
Genndy Tartakovsky’s Clone Wars Volume 1 (listed on D+ as Clone Wars 2D Micro-series)
Genndy Tartakovsky’s Clone Wars Volume 2 up to 15:24
216 Cat and Mouse
116 Hidden Enemy
The Movie
301 Clone Cadets
105 Rookies
119 Storm Over Ryloth
120 Innocents of Ryloth
121 Liberty on Ryloth
122 Hostage Crisis
205 Landing at Point Rain
206 Weapons Factory
207 Legacy of Terror
208 Brain Invaders
212 The Mandalore Plot
213 Voyage of Temptation
214 Duchess of Mandalore
220 Death Trap
221 R2 Come Home
222 Lethal Trackdown
302 Arc Troopers
310 Heroes on Both Sides
312 Nightsisters
313 Monster
314 Witches of the Mist
315 Overlords
316 Altar of Mortis
317 Ghosts of Mortis
321 Padawan Lost
322 Wookiee Hunt
414 A Friend in Need
419 Massacre
420 Bounty
421 Brothers
422 Revenge
502 A War on Two Fronts
503 Front Runners
504 The Soft War
505 Tipping Points
506 The Gathering
501 Revival
514 Eminence
515 Shades of Reason
516 The Lawless
517 Sabotage
518 The Jedi Who Knew Too Much
519 To Catch a Jedi
520 The Wrong Jedi
601 The Unknown
602 Conspiracy
603 Fugitive
604 Orders
610 The Lost One
611 Voices
612 Destiny
613 Sacrifice
Genndy Tartakovsky’s Clone Wars Volume 2 starting from 15:25 or search Youtube for “Full Battle of Coruscant” (highly recommended)
709 Old Friends Not Forgotten
710 Phantom Apprentice
711 Shattered
712 Victory and Death
From here you can hop straight into REBELS and watch that all the way through and you’ll be 100% prepared for AHSOKA.But if you had a good time making your way through this list and want to watch more. Here are some bonus arcs to consider:
The Malevolence Arc 102-104
The Citadel Arc 318-320
The Umbara Arc 407-410
The Zygerria Arc 411-413
The Deception Arc 415-418
The Clovis Arc 204, 605-607
The Bad Batch Arc 701-704