After the player defeats him once, he will take Yugi's Deck currently in exhibition the next day after class and ask for a rematch, returning the Deck once he is beaten again
There is a long history of Pokmon cards requiring three Energy types to attack, going back 24 years
That is the best guess we have, because what else could it be
These big boys are instant big threats, and they are going to be extremely difficult for your opponents to deal with
Harnessed Lighting: [Category 3] ETB yield is 3 Energy for 2 mana, then you can spend 1 Energy for each 1 life hit to a creature
The main differences to pay attention to with Light/Dark Pokmon is the aesthetic (Light Pokmon cards feature serene, heavenly art and Dark cards feature the opposite) and their attacks