The true best Dragon Type for Unova Battle Tower: Haxorus

I've won lots of Unova runs to save shinies and finding legendaries for Pokédex using Bagon or Gible as starter.

What I noticed is that you just have to find a decent special attacker for Clay a Fire or Fighting type for Colress, while your Dragon starter can do the run alone (or if I find PorygonZ it can solo all the game except for Colress)

The true hard point is N because it can copy your bonuses and doubling them.

If you go with Salamence it copies that infamous Flying type bonus: one dodge and it will reverse sweep you.

If you go with Garchomp it copies your Ground type bonus and so you can't sweep with a physical attacker.

So I tought that the true best solution is Haxorus. It has even more Attack (147) while keeping a similar Speed tier (97) so it will sweep everything. Haxorus has the advantage of not giving a Flying or Ground type bonus to N so you can't lose by hax (and speaking of Hax... your HAXorus will safely sweep it).

What do you think about? Do you also think Haxorus is the best choice?