Drapion is one of my favorite Pokémon. Its Dangerous Stinger attack can mount a comeback or set up checkmate. It can KO Pokémon without activating Raihan or Teammates, and it can take out your opponent's largest attackers. An attack cost of 4 energy is somewhat steep, but very doable with the amount of pressure this deck can put on. Even though it is possible to simply switch out of the active spot, using N alone can severly limit your opponent's options. Drapion doesn't even have to take the next KO, you can go Drapion -> Blacephelon to really cause some trouble.
Some of my favorite combos are Articuno + Parallel City, or Articuno + Klara. Multiswitch is my favorite individual card because of how versatile it is. Oftentimes, your opponent will attempt to Boss KO an attacker with energy on it or Boss KO Malamar, preventing you from accelerating energy. Multiswitch acts as insurance which allows you to load a bunch of energy on the board without putting it all onto one attacker. If your opponent decides to Boss KO Malamar, you can keep the tempo going with Multiswitch, then set Malamar right back up and be assured it will stick the rest of the game most likely. In a pinch, you can even use Multiswitch with Articuno to accelerate energy to another Pokémon.
Gardevoir and Musharna allow you to easily draw through your deck, giving you a lot of options in your hand. Using Musharna's ability before Gardevoir allows you to increase the likelyhood of accelerating energy with Gardevoir's ability as well.
Final tip: You can use Blacephelon, the Spell Tag, and even Giratina to ensure Drapion is doing exact math to take a KO with poison. Getting a knockout in this way is very powerful!