[Oh hey, it's you. Dave perks up a bit and adjusts the feed so Terra can see his Leafeon rolling around.]

Sounds like your master was a wise badass. Anyway. You don't always have to do the type advantage thing, working with what you've got is okay but arm them with a variety of moves. I like to slap down status effects and moves that keep boosting my pokemon. You got some good advice, studying the gym you're up against is a good point to start from.