You can only get those from winning enough in tournaments though. The only thing a less skilled player can trade is pikachu clothes. Besides, how long have you been playing? A newer player would have to play quite a while to build that up, where as in arena after a while, getting a new deck is...
I've been keeping my eye on TCG Player and Ebay for the prices of Shiny Value cards (from Hidden Fates) and I've kinda realized the prices of the Eeveelutions have doubled, and in some cases tripled in prices in nearly a month. I don't know if the quarintine has anything to do with it, but I...