How did Zordon choose the Rangers?

[Powermaster]

I think its a combination of the Command Center computer and the profiles Zordon had about Angel Grove teens.

[Byron Stinger]

I think thats likely the case. It wasn't as complicated as it seemed.

[MattEmily]

Originally Posted by Movie Ranger

The power coins chose them. Thats why they needed the Sword of Light to forcibly reassign. the powers to new users.

I don't know if the Coins had chose them but that's not why the Sword of Light was used to forcibly re-assign their powers. How do I know this? Because of what Zordon himself says in regards to the Sword.

Here's something that I'm quoting from a website.

Why didn't Kim need the Sword of Light in order to transfer her Pink Power Coin to Kat in Season 3?
That's a good question but I believe there are a few points to make. For 1 thing, it was just 1 Coin being transferred, the Sword of Light is only used when it comes to a great deal amount of power being transferred. Zordon basically said as much in "The Power Transfer" when it was found out the Mastodon, Saber-Toothed Tiger and Tyrannosaurus Coins would have to be transferred. Here's the short conversation after Zordon said that a power transfer must be carried out, Tommy had asked "Is it possible?" and Zordon replied with "It is possible but very difficult, because of the enormous amounts of power required, the transfer can only be achieved in one place, you must travel to the Deserted Planet."
Secondly, Kimberly's Coin wasn't linked to her life force anymore so she wasn't as bonded with it most likely due to the power source being altered.

Originally Posted by Time Force Traitor

That was always confusing..Especially since a lot of later seasons have good reasons why the Rangers were picked.

I disagree in fact in most cases the powers are just given to them.

Originally Posted by Jungle Master

Zordon did seem to have a way of knowing things that most people didn't know.

I think it was just because he had tied himself to the Morphing Grid which is why he knew so much.