The best and most obvious Sliver upgrades are the flashy 5C ones: Sliver Overlord, Sliver Legion, Sliver Queen, and The First Sliver
The competitive landscape of Pokmon TCG Pocket has seen huge changes with every expansion introduced so far, so all the strategies listed here could become obsolete in a months time
In fact, the only connection to real world money is the redemption of code cards from physical TCG products so you can have those cards and cosmetics in the game, but even those can be acquired digitally with in-game currency without ever having to spend a dime
These are all the cards illustrated by sui for Pokemon Trading Card Game Pocket (PTCGP)
My ranking: Kinda Fun Cleopatra, Exiled Pharaoh I love Golgari, so I might be biased, but a Golgari legendary sacrifice deck seems incredibly fun