[quote=@Dead Cruiser]
EDIT: Another nitpick, but looking at the OP, Planeswalkers do not have the inherent ability to time travel. Karn could only time travel because he was specifically designed to do so by Urza, a master artificer, and even then it had apocalyptic repercussions. Sarkhan traveled through time because of some weird ghost that Ugin left behind (it's not really adequately explained), not by his own power.
[/quote]

Technically speaking, ALL blue and/or white planeswalkers can time travel even post-mending. All they need to do is go to Esper, pay tuition fees, and study Clockworking.

But that's a pretty gimmicky, weak sort of time travel.