Am I Good?

More legendaries!! Ho-Oh, Raikou.

A Gardevoir would be nice.

Solid looking line up for your level. I would try and get a good Egg and Machamp though. Both very useful Pokemon.

A Blissey to retain gyms better in emergencies, a Machamp, a Raikou/Moltres if possible, a couple Golems, and maybe some grass attacker like Sceptile or Exegguttor

A double grass Exeggutor (charge move being solar beam) & Machamp with double fight moves (charge move being dynamic punch) are solid, useful pokemon to have in your lineup.
If you get a shot at any legendary electric pokemon get one.

The question 'Am any good' is the wrong one
You mean how good is my top 12 for my level, presumably as a non cheat.

And the answer is its a decent top12.
The next part of the question what do i need is more complex i would say a blissey to encourage people to leave the gym alone until it softens up a bit.
And to start preparing for kyogre which is raikou if u have them, zapdos, jolteon etc if u don't.

As a side note dont you have any groudon,weather boosted groudon would be better then your rhydon without any spend.

Machamp, Raikou, Groudon, Golem and Kyogre when it arrives

You have some great generalists. A powered, 15 attack Mewtwo is definitely above the "normal" par, so that's beyond good! However, it doesn't look like you have a lot of type diversity, meaning you'll be able to take on most challenges with that, but won't specialize well.

You can now find rhyhorns that can evolve into 2900+ cp.
Try that too.