When did Piccolo learned how to use Light grenade?

[Let's Go Fearless!]

Do you thing he learned it after merging with Kami?

 

[SSJ2]

Probably in the 3 year gap. Piccolo developed the Makankosappo in 5 years, so I can see him developing the Light Grenade in 3.

 

[Future Warrior]

I agree with SS, he probably didn't have the time or opining to use it when they fought the Androids initially.

 

[sei'taer]

It's Nail's ultimate attack he never got to use on furiza.

In seriousness, the 3 years works as well as anything

 

[Papasmurf]

On Kaio's while gangbanging Chaozu