I also love to play indie-formats and Cube
He seeks to take down KaibaCorp as revenge because he feels that Seto Kaiba stole his plans for holographic Dueling technology
That's very strong, and many commonly played 3 or smaller toughness Commander Classics are killable with this, like Hate Bears like Esper Sentinel, Goblin Welder, Flametongue Kavu, Eternal Witness, Soul Warden, Ravenous Chupacabra, and loads more
Now a Fighting type, in contrast to usually being a Metal type, this Zamazenta may not have huge HP, at 110, but it can be tricky for an opponent running a certain kind of Pokmon
Go for cards that show up in a multitude of decks so that you can switch if youre not happy with your choice
For example, suppose that on the draw, our opponent led with a 2/2 on turn two and a 3/2 evasive on turn three, questing with the 2/2 before passing the turn