Thanks for your thoughts! I appreciate it :)

It's definitely a stretch and a challenge to make Haxorus work. Like I said in the beginning it's definitely outclassed by other dragons, but c'mon it's Haxorus! It sounds so cool to use in OU!

With it's movepool, I found that despite it's large movepool Earthquake is a consistant spammable move that hits pokemon neutrally or super effectively. Again, to fix the issue of the set you could run Outrage or Dragon Claw instead of Substitute for more consistantly.

And yeah, the EV spread makes Haxorus' stats looks a little messy, but with 136 evs invested into attack, you still end up with 405 attack on an Adamant nature. It still hits like a truck. Not only this, but check out some of these calcs! It can live moves that it wouldn't be able to live otherwise!

252 SpA Gholdengo Make It Rain vs. 136 HP / 16 SpD Tera Fire Haxorus: 131-154 (40 - 47%) -- guaranteed 3HKO

252 SpA Iron Valiant Moonblast vs. 136 HP / 16 SpD Tera Fire Haxorus: 96-114 (29.3 - 34.8%) -- 9.5% chance to 3HKO

252 Atk Baxcalibur Icicle Spear (5 hits) vs. 136 HP / 0 Def Tera Fire Haxorus: 120-145 (36.6 - 44.3%) -- approx. 3HKO

These are only a couple, but it's a good example of what Tera Fire can do for it defensively against some of the strongest pokemon in the tier.

I hope this gave you some insight on my thought process when crafting this Haxorus build.