[Meta thread] Iron's PokeRole Adventure: The Skull Ruins

[Dragonstrike]

But Shadow Claw for itself doesnt have any extra effect like in the main. Its just a damage ghost move without any other effect. But Shadow Ball can actually reduce the defenses of the foe, with is WAY better than Shadow Claw. I can save some XP to teach other move for Trevenant, like Forest Curse.

Shadow Claw does have an 'effect': it's a high crit move.  That's all it does in the games, too, besides being one of the rare instances of a physical Ghost type attack.  With Shadow Ball, you have a 1/6 chance of reducing the foe's Defense by 1.  With Shadow Claw, you add 2 dice to your damage pool if you roll 4+ successes (3+ if you have Super Luck).  I think SC is arguably better so long as you don't need Shadow Ball's range for anything specific, as buffing yourself tends to be a lot more effective than debuffing the enemy (unless said debuffs are potent and/or semi-permanent).