latios latias pokemon card GX Colorless Buster Purge (240) Discard 3 Energy from this Pokémon The Cards Of Pokémon TCG:

These are all fine cards on their own

Yes, you can counter a triggered ability with specific cards that say counter target triggered ability. Regular counterspells like Counterspell only work on spells, not abilities already on the stack

It only uses cards with the true partner mechanicno partner with, backgrounds, or any of the other partner offshoots

See here for a full deck guide on Edgar Markov

In the case where Fealty to the Realm is enchanting a creature but there is no monarch, the second ability will create a control-changing effect with the timestamp mentioned above, but that effect won't do anything until a player becomes the monarch