Go ahead. Most of the info was from his timeline.
Timeline is outdated and missing some info, but still accurate. However, you'd think people would be aware of the Zero Collection site's information in regards to Zero's backstory... guess I was wrong....
1XX years ago
The birth of Zero
Zero was produced by Dr. Wily, who schemed at taking over the world. But he contained a flaw in his cognitive program that made him violent and unwilling to obey instructions, so Dr. Wily himself sealed Zero in a capsule.
1XX years ago
Zero awakens
Receiving information of Zero awakening from his capsule and causing violence, the Maverick Hunter Sigma finds and intercepts him. during this incident, Sigma is infected by the unknown computer virus leaking out from Zero’s capsule, but at the same time Zero, having his armor damaged in the battle with Sigma, also becomes infected with the virus. Due to this, Zero’s personality completely changed, and he would turn to working as a Maverick Hunter.
He would be a fully playable character in all subsequent installments, including the Game Boy Color-exclusive Xtreme series.
Only Xtreme2. But that is the one chronologically after X3.
His power and abilities are much greater than that of X
After X1, this is rubbish.
During the events of Mega Man X5, he finally did what he was created to do, and fought X in a battle that was supposed to be to the death.
After the X series, he seals himself up for a century, only to be awakened in order to save the Resistance in the first Mega Man Zero game on Game Boy Advance.
Leaving X6 out of things is just plain wrong. X7+ too, but on a lesser note, as it is X6 that ties into Rockman Zero. And you made the incorrect assumption that the sealing leads directly to Energy Crisis incident; after more than 50 years its interrupted by Elf Wars, Zero's copy body and yet another one hundred year seal.