throw him in the water
Ohhh huh. HES A DEVIL FRUIT EATER. Duhhh.
well thats kiinda tricky i mean now he has an offensive devil fruit
he can just pull you in with his darkness than punch you with gura gura no mi
my best guess would be laser blasts or piercing in general
his durability to blunt attacks surpasses that of the rubberman
he isn't terribly fast, just shoot him, then when he tries to suck you in, just stab or keep shooting him, any non-DF reliant strategy should work, and pretty much any powers are still at least somewhat effective, just attack him while you're being sucked in, and you can essentially pick any place to attack him you want to.
I think now that blackbeard is a yonkou he is much more experience in a variety of ways. I'm sure many strong fighters have attacked him enough to the point where he is more familiar with how to avoid damage and etc, rather than just taking the hits like he normally does... plus he must have a massive fleet that would protect him so that he doesn't have to lift a finger.
I think the best way to fight him is to make his df work against him and of course be a well versed haki user.
I don't know about the large army part. But he definitely is a though bastard. Hopefully Shank's and Luffy will some how kick his ass in the future.
Also, let's say if Luffy was able to fully put arnament haki onto his body like Vergo. Would an attack like Blackbeards black hole affect him? And if he took on one of Whitebeards earthquake punches, would the arnament haki protect him?
We'll be lucky if he doesn't get a 2nd logia powered fruit that WOULD let him pass through, then he'd be pretty invincible.
Oh man. Luffy should definitely use the haki like Vergo. It'll be so cool. And yes. Being able to block the quake punches makes sense but still being able to get sucked in the black hole makes sense.
But the author shouldn't give Blackbeard all the cool power ups like that. Maybe Luffy has it too? A firefist rubber man. He'd be able to make a giant fireball and counter Blackbeards dark ball white still blocking the quake punches with the rubber infused haki. Ahh yes.
We have yet to get Vegapunk's explanation of how devil fruits work. All kinds of new options might open up later on in the manga based on the possibilities. For example, Luffy might get temporary help from a weapon that ate a fruit that has been modified by Chopper's zoan affecting medicines (like Rumble ball). Haoshoku Haki might be able to tame the demons inside zoan fruits allowing them to be controlled. Then there's the artificially created devil fruits whose effects and side effects we still don't fully know yet. Maybe Blackbeard will be tricked into absorbing a rigged artificially created devil fruit that weakens his ability to use multiple fruit abilities.
I'm going to assume that Luffy currently doesn't have the capacity to defeat Blackbeard right now; so chances are he will gain some new advantages in the future. We will be able to get a better idea which way it will go when we see Luffy defeat Kaidou. By then a lot more will have been revealed about how devil fruits work (at least artificial devil fruits) and what kind of tricks Luffy will use to defeat a Yonkou.
In short there isn't just a 4th type of haki, the other three types we have seen have a lot lot more uses than just what we're seeing.