They're somewhat rare it seems, I've only seen one myself and I know some looked for a few hours to even find one.
Actually it was the Orange Island arc, not exactly Kanto.. The Crystal Onix was very interesting, as it was strong against water but weak to fire (like a Ice type) and looked very glass-like!
I wondered the exact same thing lol. I'm too lazy too try though, and someone will probably do it eventually.
It's an Onix made out of crystal. It's completely resistant to water type attacks, besides from knockback of physical moves and high powered ranged options like a Hydro Pump. Its weakness is fire type moves though. N1nt3nd0 plz add.
Honestly, wouldn’t it be cool if it was actually in the game or the shiny color of it? I found it once but I ran out of balls. I keep getting legendaries too but I fail everytime
It would be very interesting to see if there was an evolution or not but when was this Onix form added in?