A lot of recent white hatebears feel very narrow, but Archon of Emeria doesnt suffer from that problem - it will consistently impact the game when it shows up on the battlefield
The Borderless version is also the absolute definition of a collectors item if I've ever seen one, and proving to have plenty of interest as well
(A copy of a permanent spell becomes a token.) A single survivor can repopulate a devastated hive within a week
For instance, check out subreddits like r/pkmntcgtrades and r/PokemonTCG, or the Pokmon TCG Sell and Trade Facebook group
This could either fuel Metagross-GX itself or whatever Psychic- or Metal-type was used with it
In summary, if you're wondering about the best way to sell Pokmon cards in bulk, the answer lies in preparation, organization, and choosing the right buyer