Dragon/electric versus grass/poison, if we're going with that reference. More or less balanced back out to neutral on the typings when the former uses dragon and the latter uses poison. It's impossible to make a dragon type especially weak to grass, and only dragon/fairy is especially weak to poison. Dragon/steel would be immune to poison and highly resistant to grass so that one would be an interesting opponent to throw at our Tang San pokemon equivalent. Of course if we really wanted to go down this rabbit hole, you can consider most of these people as having various other typings for some of their moves. But I already spent way too much time thinking about a reference that took someone else five seconds to make seven months ago.