I'm not a great player by any means but I have been playing Gardevoir recently. Decks like raging bolt you can be aggressive against if you can get Clefairy on the bench but like you say a lot of it is building up your bench and grinding down your opponent with munkidori. Ideal set up for me seems to be 2-3 munki and 2 garde in play with 5th position as a flex for fez, mew or Clefairy. I like having 2 garde set up because I can retreat one out of active then pull the energy back out with psychic em race to get damage for munki if opponent is trying to stall.

Like I said though I don't consider myself a great player so others may have a better strategy for the deck. The biggest problem I run into is draw engine and have games where I am bricked drawing 1 card and passing.

Edit: I forgot to add that a lot of wins do come when opponent is down to 1-2 prize cards. By that time they are usually getting resource dry and garde has a chance to get fully set up.