>>51626966Honestly i don't give a fuck what ability he has.
Truant is unironically kino and makes for Slaking to be a really fun Pokemon for single player. It isn't a Regigigas situation either: You get Slakoth very early in RSE so you know what you're getting into, and Vigoroth gives you the ability to sacrifice those stats in exchange for being able to move every turn.
Unfortunately in comp Slaking is basically useless outside of some niche Doubles ability fuckery (I'm looking at you Evice and your Skill Swap Slowking).
Either way he's fun and really helpful in both regular playthrough and in challenge runs. Hell my Slaking carried me through an Emerald nuzlocke. He's great for using a move and then pivoting to a Ghost type to punk the AI into using Fighting moves.