As with everything, unless abilities are introduced, all that matters is movesets. Groudon will forever be the champ at ground offensive unless they introduce other better ground type moves and give them to other species. Hydreigon could become a tenfold better dark type attacker than Ttar if it got better dark type moves, simple as that. Having said that, Hydreigon is one of my favorites so I'd love to see him get some use when it is introduced
About the "best attackers": Dark Type
So I've seen this stated many times; the next dark-type that could potentially threaten Tyranitar's reign is Yveltal. Yeah, that makes sense and all. Yveltal is a great Pokemon in the main games and stands to have the potential to be a nightmarish dark-type attacker. But is it really the only contender to the throne?
I don't have access to its exact stat-build, but what about Tyranitar's fellow pseudo-legendary from Gen 5, Hydreigon? Its dark/dragon typing makes it arguably better in comparison, and its offenses SHOULD edge out tyranitar by just a hair.
Base Atk+Sp.Atk for Tyranitar in the main games: 229
Base Atk+Sp.Atk for Hydreigon in the main games: 230
....true, Tyranitar's 3670 max CP VS Hydreigon's 3401 does reveal that Tyranitar has substantially more bulk. However, all that it would take to tilt the scales would be a better dark-type moveset (assuming that's even possible. I have not looked at a list of current dark-type moves and compared it to what Hydreigon can learn in-game) to potentially put it on a par with Tyranitar.
...and yes, I also know about Bisharp, but given its lack of tools that make it good in the main game, didn't even really look a t it.
Any thoughts?
Answers
True, but looking over Hydreigon's real moveset, it's most likely going to have Crunch/Dark Pulse for dark movesets, and the only real hope for future movesets that I can see would be if Brutal Swing turns out to be a dark-type Solar Beam (Possible in my opinion. Solar beam has 120 BP but takes 2 turns to execute [in most cases], making it 60 BP effectively. Meanwhile, Brutal Swing is 60 BP).
Base stats in POGO:
Hydreigon Atk 256 Def 188 HP 184
Tyranitar Atk 251 Def 212 HP 200
Unless I miscalculated Hydreigon's stats, it looks like Hydreigon can indeed challenge Tyranitar with a small advantage in attack but lower tankiness. Hydreigon with Bite/Dark Pulse (seems like a very likely moveset looking at its movepool) would be the go-to Dark attacker, better DPS than Tyranitar and tankiness very similar to Moltres.
Wouldn't think that tiny difference in attack is worth that significant difference in bulk. Ttar will still beat it out barring moveset. It looks cool though and it's typing might creat a niche for it. They might also introduce megas at some point as well. What would yveltal be without oblivian wing and there are no healing moves in the game.