How to coat popcorn with flavor

I think this is primarily going to come down to the method of cooking and the flavorings. I think it's unlikely that you can buy a microwave popcorn that will taste like the movie theatre.

You'll need a specific popcorn pan so that you can stir the popcorn continuously and that will also vent some of the steam from cooking (which a normal pot won't do. Whirley Pop seems to be a common solution here.

Next you'll need to find the right type of oil. Experiment with a couple of things to see what you like. Coconut oil seems to be commonly recommended (and not easy to find).

Finally you'll need flavoring. Try Flavacol. My work has popcorn on thursdays, and they use this flavoring. It's pretty dead on.

I don't think the actual pop corn kernels will make a ton of difference. It's more the cooking technique and other ingredients.

Here's my primary source, but further research and experience backs that up as pretty dead on.

While movie theaters do often add flavoring agents (e.g. Flavacol) during cooking, that's not all they do for seasoning— they also use popcorn salt which is simply extremely finely ground plain salt. Morton, among other salt companies, package it for sale in grocery stores. It sticks perfectly to popcorn with absolutely no liquid or fat whatsoever. If you can't find any, and don't feel like ordering it online for some reason, putting salt into a high speed blender, spice grinder, mortar and pestle, or some other grinding device does the trick.

For a sweeter corn, you can use a shake of confectioners sugar. It would be great with a shake of cinnamon.

I love to add a touch of garlic powder and a shake of smoked paprika to mine! My wife absolutely swears by brewers yeast for her popcorn... she even brings a little jar of it with her to the movie theater.

Good luck and happy popping!