Pyroar isn't the first Pokemon that comes to mind when you say "OU viable", as it get abilities that limit it's potential. It does have decent Speed and SpA, but that can only take it so far tho in OU. Pyroar will shine better in lower tiers. I have only tested it a few times with a Scarf and Life Orb Set, but the Weakness Policy set by Private Affair seems very good and promising!!
Pyroar @ Weakness Policy
Ability: Unnerve/Moxie
4 HP/252 SpA/252 Spe
Timid Nature
~ Substitute
~ Fire Blast/Flamethrower
~ Hyper Voice
~ Hidden Power Fighting
This set will allow it to set up a sub against pokemon that can OHKO, get a +2 boost and then can potentially sweep an entire team.