It doesn't seem like your current team is very well-rounded - no offence meant. You have two fighting types, a pure grass, electric and a pure fire type.
Pure typed pokemon aren't very good, wit quite a lot of exceptions. Unfortunately, servine and darumaka aren't in the exceptions group, whereas zebstrika and mienfoo are, so keep them. By your list, it seems you're mid-game, so I will use unova-only pokemon in my list.
If you use zebstrika and mienfoo as I recommended, it covers only 7 types, if you use only fighting and electric type moves, so you need to cover the other 10 types. You have to combat dragon type pokemon for the 8th gym, so get an ice type early, that's where your vanillite comes in. Vanillite also combats flying pokemon as well as zebstrika, as well as grass and ground, neither of which zebstrika or mienfoo can combat besides a flame charging zebstrika on grass. He can also charge down bugs and ice. This is now 13 different types with 4 left, actually, vanillite can learn flash cannon and mirror shot, they're steel so that's 14 with 3 left.
This leaves us with fighting, ghost and psychic. Fighting is weak to flying and flying is neutral to the others, so a dual typed flying pokemon could combat this... a bug and flying can kill 2 birds with one stone since bug is good on psychic... a unova bug+flying type is... there isn't one. How about flying and dark to hurt both ghost and psychic pokemon... VULLABY!!! My list would be:
Zebstrika
Mienfoo
vanillite and...
VULLABY!
You can fill in the final two with HM slaves, but good ones at that such as bascullin and then your starter if you want, but i'll use liligant, she's great, especially it's petal dance!