To be fair this does work in the TCG to some extent, just compare the current price for a Secret Illustration Rare Iono to the price one commanded at release date (or if you want to be completely insane, during prereleases)
The way it works is simple: if your opponent has a Pokmon on their bench that has taken damage, you can swap it to the active slot
A reasonable approximation of the expected power of gold cards is that your 2nd colour of mana adds about a 1/3rd of a mana, the 3rd colour adds 2/3rds of a mana and the fourth is a whole extra mana
Like a toddler in a sea of wrapping paper, Im baffled by all these glittering new things, but delighted by them regardless
Unlike typical abilities or keywords, Monarch is a designation a player can hold, transforming the flow of the game by introducing a high-reward, high-risk element to the multiplayer format