For Electric types, either get Eelektross or Jolteon. Even Ampharos does a good job, but i imagine you don't want to backtrack all the way to Flocessy Ranch to get a Mareep. I say, get Eelektross. Sure, its molasses speed cripples it just a little bit, but the variety is insane, so it's impossible to just pick one set. I'd say arm it with Wild Charge/Thunderbolt, Flamethrower, Acrobatics/Crunch, and Dragon Claw.
You should stick to Crobat, since he's the fastest member of your team and can also land good damage with excellent moves and annoy the opponent with Confuse Ray.
Lucario and Zoroark on the same team are forces to be reckoned with. You should definitely keep those two, since they're both mixed sweepers.
You should only evolve Growlithe (i'm assuming you still have a Growlithe) after level 45. Your moveset should be Flare Blitz, Outrage, Crunch and some other move by then. Or you could always evolve it at Level 34 and gain access to ExtremeSpeed, which can also be learned via Move Reminder.
I don't really know if you'll use a dragon, since dragons are mainly Physically attacking beasts and you already have two pretty strong mixed sweepers. But if you do, i'd suggest get Haxorus, Flygon, Druddigon or Hydreigon. Haxorus has the biggest Attack stat of them all, towering in a mindblowing 147 base stat. Flygon is probably the least recommended since it's extremely underpowered but can pack a good punch if you use it right. Druddigon is the tanky dragon that can also deal some pretty good damage. Hydreigon's the resilient special attacker that can learn moves that cover nearly all of its weaknesses.
I see why you're not planning to have a Grass type. All the types that Grass is super effective on (Rock, Ground, Water) can be easily countered by a Water type (Rock, Ground) and an Electric type (Water).
Anyways, that's it. Hope i helped!