Nidoking's Poison Horn may be a bit high-cost, though making the adversary Poisoned will eventually pay off if the foe does not heal and remove this special condition
That'll surely help him in his Island Challenges right
If you attach a Water Energy to Totodile, for example, it will only let you perform its first attack
For example, some of the most expensive Pokmon cards ever sold have been Japanese cards, including the most expensive card, Pikachu Illustrator
Unlike almost every other format or game type in MTG, a planar deck such as this one can easily be copied & proxied up to play with your playgroup, as most people won't mind too much, (except maybe your local store owners) Also, due to the fact that Planeschase usually goes hand in hand with casual formats, people are also going to be more lenient, since there isn't a lot of money or worth in the plane cards themselves
Good sellers can alert you when cards you are looking for become available, or advise you on pricing trends