So trying to map out to what degree canon storyline I can reasonably incorporate into a Plane Shift: Zendikar campaign, and my OCD forbids me from making planeswalker characters without use of their appropriate racial statistics... so... from Zendikar to Innistrad, if I were to reenact the storyline (with alterations made by the party) I'd need Nissa, Nahiri, Kiora, Chandra, Jace, Sarkhan, Gideon, Ugin, and Sorin, and with Art of Zendikar, Art of Innistrad, and soon to be Art of Kaladesh, and expected Plane Shift: Zendikar, Innistrad, & Kaladesh, that should yield racial stats for Nahiri, Kiora, Nissa, Sorin, Tibalt, Arlinn, (probably Vronos) Chandra, and Saheeli so far. I'll expect I'd need to cross my fingers for a Vryn block, Return to Theros, Return to Tarkir, and Return to Dominaria for us to get Art of Vryn, Art of Theros, & Art of Dominaria, and thus Plane Shift: Vryn, Plane Shift: Theros, Plane Shift: Tarkir, & Plane Shift: Dominaria to build up the stats for Jace, Gideon, Sarkhan, Ugin, & Liliana.

More to the point, I'm trying to tip-toe in that general direction rather than dash, so was seeing if anyone could help with filling me in one what planeswalkers were present around the same time on Zendikar...

I know 1 (Nahiri) 2 (Nahiri & Sorin) 3 (Nahiri, Sorin, & Ugin) 4 (Nahiri) 5 (Nahiri & Nixilis?) 6 (Nissa, Kiora, & Nixilis) 7 (Nissa, Kiora, Nixilis, & Sarkhan?) 8 (Nissa, Kiora, Sarkhan, Nixilis & Chandra?) 9 (Nissa, Kiora, Sarkhan, Chandra, Nixilis & Jace?) 10 (Nissa, Kiora, Gideon, Nixilis & Sorin?) 11 (Nissa, Kiora, Nixilis & Gideon off-and-on?) 12 (Nissa, Kiora, Nixilis, Jace/"Planeswalker", & Gideon off-and-on?) 13 (Nissa, Kiora, Gideon, Jace, Nixilis, & Ugin?) 14 (Nissa, Kiora, Gideon, Jace, Chandra, Nixilis, & Ugin?) 15 (Nissa, Gideon, Jace, Chandra, & Ugin?) 16 (Nissa, Gideon, & Ugin?) 17 (Ugin?)

Most importantly, what was the order of earliest flow of planeswalkers in and out of Zendikar since the Mending?

I'd need some time to disentangle that, but I'm just popping in to say that Garruk has been to Zendikar as well (before the events of the first Zendikar block).

Hasn't Garrul been to Zendikar post veil-curse too? In the 2015 game I thought he followed the player character there after you got the Hedron from Ob's head.

Legitimately not sure if he followed you there or if you had to chase Garruk down to put the Hedron in his head, I never got to play that version.

Can you maybe put line breaks in between the numbers? That's incredibly hard to read

The earliest thing we know is that Nahiri's spark ignited sometime before 5000 years ago, because that's when we started galavanting around with Ugin and Sorin.
We actually know very little about pre-Eldrazi Zendikar except to say there were civilizations there that are no longer present.

So, I took some time to dig through your list, and overall it looks pretty accurate. I'd insert Garruk between 6 and 7 (which means you'd have a point where Nissa, Kiora, Ob Nixilis and Garruk are on Zendikar). I'd take Kiora out of 11 and 12 because that's probably where she was travelling the multiverse in search of big sea monsters to fight the Eldrazi. 16 should probably have Chandra as well (so, Nissa, Gideon, Chandra, Ugin?), because she's still there when Jace comes stumbling in from Innistrad to get the Gatewatch. Then you could have a point between 16 and 17 for the brief moment when Jace is back (Nissa, Gideon, Chandra, Jace, Ugin?).

The thing Vega said about veil-cursed Garruk returning to Zendikar could be true, but I don't play the Duel games and have trouble keeping up with some of the details from there, so I haven't got a clue.

Edit: Nahiri was around sometime before 6,000 years ago rather than 5,000, though. You have to keep in mind that the stories that say 5,000 already took place 1,000 years ago themselves.

Oh okay, then it's not currently doable considering Sarkhan gets a foot-hold at the Eye of Ugin early on, and I haven't the intended stats for a Tarkir human. Hmm, though similar with Ob Nixilis (I can see him being played as a beefed up "generic" demon, hmm, Sarkhan could be a generic dragon I suppose.... bringing up a good question: what species of dragon does Sarkhan model his dragon mode after?

So if I wanted to play out a campaign featuring the release of the Eldrazi Titans, I'll need Plane Shift: Vryn in addition to what's confirmed.

It seems to be a red dragon, probably of the huge size category.
An argument could be made for him being a very dirty brass dragon though, but that's largely cosmetic.

Oh, okay, that makes sense, but I was considering what type of dragon Sakrhan himself becomes. He's a red-colored firebreathing dragon, but no horns, so CLEARLY not an Atarka brood.

Oh, yeah, no, that's pretty clearly a Jund dragon.

You're doing separate stats for the humans of each plane? That is.... a lot of extra work, and doesn't seem liek a good payoff.

Humans are supposed to be the baseline of each plane. It was why Lorwyn was so unique - it didn't provide that baseline comparison to say "this is how this race is different from humans" in that hamfisted way WotC likes to do.

If I remember right, in old Zendikar Planeswalkers were this semi-known quantity among the locals, so it is safe to assume that a lot of Planeswalkers passed through there.
Obviously all the Planeswalkers mentioned since Origins were from there.

Also, how sure are we Nixilis wasn't there for the Eldrazi invasion? Seemed that he knew a decent amount about the Eldrazi in the new stuff, aftrer all

Considering Plane Shift: Zendikar and Plane Shift: Innistrad differed greatly on stats for humans, and Zendikar gets vampire by default, whereas Innistrad vampires require you use their human stats and play as a vampire using the "Play as a Vampire" rules from the Monster Manual, adjusted to Innistrad's vampire monster stat block, they must be different depending on plane of origin. If Plane Shift: Kaladesh portrays humans the same way as Zendikar, then I can concede that the variation between Innistrad humans and all other humans is the focus on humanity on Innistrad, thus the specially crafted stats.

Wait, there's a Plane Shift: Innistrad? When did that come out?
Also, I think that the difference there is more major between the Vampires of Zendikar and the Vampires of Innistrad. On Innistrad, there's only the one type of Vampire, a race. On Innistrad, there are 4 houses that are converted humans.

Wait, there's a Plane Shift: Innistrad? When did that come out?
Also, I think that the difference there is more major between the Vampires of Zendikar and the Vampires of Innistrad. On Innistrad, there's only the one type of Vampire, a race. On Innistrad, there are 4 houses that are converted humans.

I mean, at least with planeswalkers, it makes a lot of sense to largely ignore what hypothetical stats their homeplane might assign to their race. The special thing about them is that they transcend their plane of origin and pick up new tricks all around the multiverse after all.

That's the thing though, besides Ob Nixilis appearing as a demon instead and Sarkhan appearing as a dragon instead, planeswalkers don't change races ultimately (unless my theory that Sarkhan Vol is destined to become Ugin himself is proven, basically meaning that Ugin is born on Tarkir as a human, becomes a planeswalker due to his other self, learns to polymorph into a Jund dragon, and eventually that dragon form becomes necessary and thus permanent, and other magics and enlightenment leads him to become the "Spirit Dragon" we know today, who then storm-borns the actual native dragon species)

So if Kaladesh has its own human racial stats and doesn't just match up with Zendikar or something, then if I desire to incorporate most of the main players of the ZEN & BFZ blocks, I'll need Art of+Plane Shift: Vryn, Theros, and Tarkir to become a thing.

As it stands now, Eldrazi plotlines will have to wait. Perhaps I'll have to setup either a small "Adventure World" focused campaign, and/or end on a cliffhanger after adventure world but before Eldrazi plotline. (probably Chandra making an appearance as an NPC)

*takes deep breath*
No.

I wasn't just talking about literal transformation or changing race, though. With Sarkhan being born on Tarkir, transcending his clan's colour combination, becoming a planeswalker, encountering dragons on a variety of worlds (which already sets him apart from everyone on Tarkir in his old timeline, where dragons are extinct), learning how to turn into a dragon himself, serving Bolas, and being driven mad, I don't think he'd still share the same old outlooks, skills and abilities (read: stats) as the average person on his birthplane, no matter which clan they're from. Ergo, you don't really need Tarkir human stats if you want Sarkhan to show up.