Remember that holding the X items doesn't actually boost their stats, you must use the item itself during a battle. Here are a few suggestions for your team.
Typhlosion-High Defense isn't the way to go with him. His base defense is too low for it to do anything worthwhile. Instead, you should invest in his special attack. You also have way too many fire type moves on him. I'd just stick with eruption. Blast burn is powerful, but the recharging is like doing 75 base power each turn without STAB. He could use other moves like Hidden power, focus blast, extrasensory, etc. You can also take advantage of his physical movepool by using moves like Rock Slide, brick break, or thunder punch.
Luxray-Once again, too many moves of the same type. Keep thunder fang since you say yours has high attack. You can cover his ground weakness with Ice Fang. Crunch, Thunder Wave, and Return are all good moves for more type coverage.
Infernape-Too many fire moves. Give him Flamethrower or Fire Punch so he can have a decent, dependable move. With him you can use stone edge to deal with Flying types. Swords dance is great for boosting his power up. Mach Punch is a good priority move, or you can use U-Turn to deal with Psychic types while getting safety.
Mightyena-His special stats are too low for anything to be effective. Instead, give him Crunch for STAB, or Sucker Punch For priority. You could give him something like a toxic Orb and use Facade for double damage. Mightyena, while a cool pokemon, is far from the most effective.
Staraptor-All flying type moves is a bad idea. Keep Fly if this is for In-Game. Return or Double Edge is good for a STAB move. Close Combat is good for all out power. Roost can be used in conjunction with recoil moves. U-Turn and Facade are both good moves for him too.
Houndoom-Drop Fire fang and fire Blast. Replace Crunch with Dark pulse since he has higher special attack. Nasty plot is a good idea for him. Sucker Punch, though physical, can be good for priority. Hidden power can be good for coverage.
For your team as a whole, I'd highly suggest changing a few members. Half of your team is fire, and you have two dark types. Mightyena isn't the greatest, but for in game, he should be okay. Also, be sure to invest in your pokemon's complimentary stats. For instance, Typhlosion is made for Sweeping, so invest in his special attack and Speed.