His cybernetics were mostly made with the intent that he's going to be stacking more armor on himself and carry heavier weapons, so he's tougher than your average human. He's an inferior model since, aside from what is essentially a greater carrying capacity, he doesn't have many other bells and whistles. Even his strength is mostly just an application of being really tough and making it go as fast as he can in the direction of something he wants to hurt. His radar itself is more or less just a satellite image he's ripping off the internet, since he effectively has a phone built into his head, and night vision which has been mechanically carried over from his life as a faunas. Honestly, he couldn't even pass as a regular faunas considering how bulky and misshapen he looks, but he gets by anyways simply by not bringing it up. When family day comes along this would be very notifiable, as his family look proportionally human while Gren is build like a space marine in full regalia.
The fact he's so heavy and dense is why he can't swim at all, such as the last mission were he was either reliant on his semblance to essentially turn water into a solid surface for him to walk on, or use a whole bunch of external devices to move him through the water in a very sluggish manner. The guy is easily 300lbs+ even without armor, and with his weapons and everything he's a little close to 500lbs total. So you can always try to use his weight against him, like leading him to an area where a lighter person could cross safely, but a heavier one would struggle. His size is, of course, another issue, since he has difficulty moving in small spaces. While his chainsaw at least allows him to do some melee as long as he can press it against the enemy, fighting him in a place where there's a lot of things in the way will limit his options considerably.
In a non combat situation, there's also a matter of self-sustainability. To put it simply, Gren can't get healed. He has to be repaired. He has an artificial blood or sorts that can deal with cuts on his skin, simulating bleeding and clotting, but actual damage to his body can't be healed with rest or regeneration, unless it works on mechanical things too. While he has an indefinite power source, if something is strong enough to damage him and he can't reach somewhere where he could repair himself, he's stuck with that injury. A broken wrist needs to be replaced, or at best jury rigged, but it won't repair itself no matter how much time Gren gives it. And while he has no problems operating during the day, and his helmet tends to dim things if they're too bright, if he's activating his darkvision you can blind him pretty badly by flashing something really bright at him. You'll know he's using his darkvision because it's really dark around him.
His rockets boosters also use it's own fuel too, and while he's going to upgrade that once he figures out how to use his aura to power a jetpack, they need refueling after extended use. Eating food helps but only a little bit, even if he eats a lot. He typically needs a very special type of biofuel he has to make himself, and unless he spends a few hours stuffing his face, once he runs out he's out until he refuels. And the fastest way to do that typically involves opening up his chest and filling up the tank, which removes all those armor bits he's been using to protect himself and expose all the important bits that keep him alive.
Again if you're looking for some sort of kyptonite or a sweet spot that'll kill him dead, it's nothing that wouldn't work on others. Aim for the face, stab him in the back, go for his arm pits, kick him in the dick. Granted, it's also why he wears armor over those parts. The only real things he's immune to is bleeding out, poisons, and diseases. For everything else, you just need to follow the fighter's first rule of enemy engagement: If your first attack doesn't work, hit it again harder.