The way I understand Nicol Bolas' story, in his long-ago "youth" of being just an Elder Dragon rather than a Planeswalker, Tetsuo Umezawa killed him or imprisoned him or beat him up and stole his lunch money.
I didn't say I understood it well.
Then, later when he had full pre-cataclysm Planeswalker powers, he met Tetsuo's ancestor Toshiro on Kamigawa and tried to kill him, a few centuries before his younger, weaker self would be punked.
Wibbly Wobbly Timey Wimey indeed.
Like with the Planar Chaos Dragons, I would like to do all 5 Elder Dragons. The problems are:
1) Pretty much nobody uses the other Elder Dragons as generals.
2) Only Nicol Bolas has a black-bordered printing that costs less than $10.
Oh yeah, and
3) I have less control over time than Nicol Bolas does.