Notes & Combos
Just the standard Gouki deck. It's hard to counter and easy to win with. You just need to remember Abyss Dweller is your biggest enemy.
Knightmares are great for removal, but sometimes you can't OTK.
Techs are interchangeable, I figured BoM and Warning Point to be equal in terms of efficiency, but in my last duels I used WP. Dark Hole and Needle Ceiling are also great options.
Expendable Dai is interesting card. It's like Fish Depth Charge, but P2W. It has great synergy with Goukis, but can be a dead card if you don't draw any warrior monsters. I think 2 is less bricky than 3.
Overall the deck has great OTK potential and is fun to play. Don't forget which monsters you sent to the GY, so you can use the search effects.
And about the skill. Three Effects is better, I just wanted to upgrade Tyranno Hassleberry.