Replace Ekans with a Togedermaru, which you can get on Blush Mountain. Keep surfing until you get 8 BP and, on Ula Ula Beach, teach Togedemaru Iron Head and give it the Steelium Z. Use Z powered Iron Head on Mimikyu and keep using Iron Head. Also, a helpful tip for defeating totems: First defeat the totem, then the ally.
If you don't want to get a whole new Pokemon, then evolve Inkay, since you are ready to. You can evolve Inkay by leveling it up while holding your system upside down.
You also have a lot of Dark types, so you should take out one or two. On top of that, Haunter will only evolve if you trade it to someone else, so maybe don't use it, either.
EDIT: I know lots of people think Togedemaru is bad, but it is actually very good if you have this moveset:
Zing Zap, Iron Head, Spiky Shield, random physical or status move.
Hope I helped!