User blog comment:Kaido King of the Beasts/Chapter 843: Thundering and Lightning, Very Very Frightening (He's Just a Rich Boy From a Rich Family)/@comment-24469584-20161020205407

https://www.reddit.com/r/OnePiece/comments/58hy98/one_piece_chapter_843_theories_and_discussion/d90ugxa

Luffy's attack Thor Elephant Gun is used on his left hand. It uses elecricity/thunder. Thor is the god of thunder.

Luffy's attack Red Hawk uses fire and is on his right hand.

He has similar powers to Big Mom. Imo it's elemental haki.