Celebi ex and Venusaur ex are two powerful choices that can leave many other types in the dust due to their overwhelming damage
However, you should have somewhere between eight or nine Traps in this build, so you should consider adding copies of Karma Cut (which have almost become a necessity in the current meta), Paleozoic Canadia, or Wall of Disruption
Moat gets played in Oldschool, Legacy and Commander
I particularly love Kogla, the Titan Ape here, since Koglas indestructible ability can be used in conjunction with Samut to save your commander from removal
Of course, when the original darkness energy debuted, it was certainly not one of the most valuable cards from Neo Genesis, but it was already a rare card and surprisingly it caused any darkness-type Pokemon to deal 10 more damage to the foes active Pokemon
Debuting at the end of season one of GX was the Sacred Beasts, a more evil version of the god cards in Yu-Gi-Oh