Okay, so its an early 90s maybe late 80s anime.

The main character used a four sided crystal to transform into some kind of Android robot

In ine episode he fought a girl with a laser whip

What is the name of this anime? :confused:

Hey Enrilimbs, I believe that the name of the Anime you're thinking of is TEKKAMAN BLADE. It was one of my favorites as a kid. Hope this helps!