So turns out the game uses the same initial seed when you soft reset.

What it means is that if you take the same amount of time to go from the Konami screen to the start of a duel (after the Rock Paper Scissors screen), you'll get the same deck orders for both players, resulting in the same actions, card draws, etc. You can get the exact same two duels pretty consistently.

I'm on other projects at the moment, but if you're interested into running this game, definitely start by reverse-engineering the PRNG.

I'm a noob on that topic, get me started, what sould I look for?

I know a little about PRNG, but I don't know how to research it in games