Well houndoom may be a fire type but verizion is a grass legendary but is both where the same level or houndoom higher, houndoom would be the choice

Well obviously Virizion is a legendary,but like I've said before,it's a title and that means it's a rare Pokemon,nothing special it's still a main grass type in which is weak to fire attacks from a Pokemon like Hellgar/Houndoom,but also Virizion is also part fighting which a part dark type such as Hellgar is weak to,so I think it depends if the Pokemon or Trainer executes there moves the right way/manner,because one is weak to the other in one way,but I believe Hellgar has the advantage.

being called legendary pokemon is just more then a title, it beens they're better then the average pokémon.

agreed

Houndoom can kick anyone's butt!!!