Looks like you've got a pretty good mix of types with a variety of resistances. The only glaring weakness that you might want to cover is Ground. Ground type attacks are super effective against 3 of your pokemon: Infernape, Luxray and Lucario. Unfortunately, Ground is a bit more common later in the game, as well as in competitive battling.
I'm big on type matching, so to counter this, I'd say add either a flying type pokemon, or something with Levitate, as your 6th.
What you go with is really up to you. There are a lot of flying types out there, so you have lots of choices if you go that route. A nice Ghost type (provided they have Levitate) is always nice to have on a team; it adds immunity to Ground, Fighting and Normal type moves. (All of which are common attack types)
I love my Mismagius, but it sounds like you've got Diamond. Gengar? Murkrow (Dark/Flying, immunity to Ground and Psychic) might be also an option. One of Uxie/Mespirit/Azlef could work, or a Bronzong with Levitate. Bronzong is built like a tank, so it can be a beast to kill (just watch out for Fire!). Do any of those catch your eye?
Hmm. Grass Knot might be interesting on Infernape, actually. I just find those weight-based moves aren't for me. And Infernape's PP doesn't look bad to me; Flare Blitz has 15, only 5 for Close Combat, but lots for Mach Punch. Plus whatever else you put on 'im.