So eh, don't both creators have to agree with a matchup before a versus thread is made? Well anyway...after reading Grim's profile in full, my take on this matchup is: Either a stomp or a inconclusive match. Why a stomp? Well, while things such as turning into Alien X or using the infinity gauntlet could help in theory, it still wouldn't do much, or in fact anything, against a guy who can tank and "wound" a Primordial from the Akashaverse. It's a tier 1-C versus a potentially 2-C character with equipment...it's pretty self explanatory. That and, Daniel could straight up stop Grim from using Mandy's Artifacts at the beginning of the battle as without them Grim is only a 7-C character while Danny at the Primordial war is easily beyond universal+ power without any boosts from Whitcher state or Ragnarok's soul.
Even without prior knowledge, Daniel is more than well-versed in pop culture, gaming, etc- So if Grim tried using weapons like the IG or the ominitrix, Daniel would just know what to expect. And although not listed yet, Danny is a counter guardian, someone who exists beyond conventional boundaries and is not affected by paradoxes, time itself, and most importantly he doesn't require a soul to function or even a corporeal form, so the soul damage would only ever serve as a minor annoyance to Danny.
As to why it could be an inconclusive match, well it's simple, there's no saying how things like Grim's death touch would affect a counter guardian who exists beyond death to some extent. Would Grim's power mimicry work at all against Daniel? It's just not enough detailed. But ultimately it comes down to how serious Danny takes this fight- If he toys around and fights Grim at his level, then both would fight until they can't anymore. And if Danny starts of even remotely up to a fight, then he'll just win due to better stats and ability to legit destroy Grim's existence altogether before any artifacts are even used.