The Flying Press Conundrum: What if There Were More Dual-type Moves
Another night, another wacky journey my mind wanders off to. This time, the Pokemon move Flying Press had me interested.
Background
Flying Press is a move with a very unique mechanism in Pokemon. Whereas other Pokemon moves deal damage of a single type, Flying Press deals damage of (multiplicatively) two types, namely Fighting and Flying. As of now, it's the only move that deal damage of multiple types and it can only be learned by the Fighting/Flying Pokemon Hawlucha.
Now, the choice of Fighting and Flying types, while fitting of its unique user Hawlucha, may actually imply a mechanical reasoning. The combination of Fighting and Flying types results in no double weakness or double resistance, that is, no single type is weak to both Fighting and Flying, and no single type resist both Fighting and Flying. There were however, types that resists one and is weak to the other.
Weakness in Pokemon is represented by a x2 (very effective) multiplier to the damage, while resistance is represented either by a x0.5 (not very effective) or a x0 (not effective) multiplier. So, all added together, Flying Press deals no x4 or x0.25 damage against any type (it does against Pokemon however, since they can have two types).
Research
With the explanation out of the way, we'll move to the question. If the mechanical reasoning is true, what other combination of two types can we expect to see in the future? I used Python to automatize this process.
Before we move to the results, there's one thing that some people may have overlooked. If you see the two sentences I have bolded above in the Background section. You might think that they mean the same thing. It's not. A combination of type can deal no x4 or x0.25 against any type while still having a type that resists both types in the combination given that one of the resistences is not effective. That is to say, x0 and x0.25 result in a x0, as does x0 and x0.
The combination of Fighting and Flying, however, has no such cases. While I don't think it would pose any mechanical problem, I'm dividing the research where such cases are eliminated and where they're not. The criterion where they're eliminated will henceforth be called the Restrictive Criterion.
Also, I'll be treating all types as equal, which may not be the case in practice. For example, you might prefer your combination to be resisted by the Bug type than to be resisted by the Steel type, because the Pokemon of the former type tend to be fragile and the latter be bulky.
Result
There are 57 possible type combinations, and 48 of them passed the Restrictive Criterion. So, I'll highlight the interesting results first and list all the possible combinations at the end of the post.
The first thing you might be looking for is what combination yields the highest number of types that are weak to it. There are two combinations tied at the first place, Ground/Ghost and Ground/Dark. They're both very effective against 7 types. They both passed the Restrictive Criterion. Interestingly, they share the same 7 types, Poison, Rock, Ghost, Steel, Fire, Electric, and Psychic. For comparison, the highest number of types that are weak to a single type move is 5, which are Fight and Ground moves. The former combination has 5 (2 not effective) types that resists it while the latter has 6 (1 not effective) types.
You might notice that both combination above still have types that they're not effective against, which means they deal no damage against certain types, if you're looking for a move that will always deal damage against any type, then the highest number of types that are weak to such combination is 6. There are two combinations here too, Fire/Dark and Ice/Dark. They both also passed the Restrictive Criterion.
We had taken a journey to find the most explosive type combination. But, what about the most reliable combination? The notion of most reliable can be represented by the combination with the lowest number of types that resist it. While the competition for the most explosive combination was very close, there is a clear winner for the most reliable combination. Flying/Ground only has 1 type that resists it, Flying. This combination also passed the Restrictive Criterion. For comparison, the lowest number of types that resist a single type move is 2, which are Ghost and Dragon. The next combinations closest to Flying/Ground each have 3 types that resist them, which is worse than the best single type case.
Update: I have written a second part of this discussion here, tackling the problem of dual typed defending Pokemon.
Personally, I find Flying/Ground to be the most interesting combination. It's rather poetic how the two types that are pretty much opposite of each other work very well together. For reference, there are already 3 Pokemon with Flying/Ground type, Gligar, its evolution Gliscor, and both formes of Landorus.
And that's it, the rest of the post is a table of all the possible type combinations, thank you for keeping up with me.
P.S. I don't know why I wrote all of this on Ameba
| Types | Very Effective | Not Very Effective | Not Effective | ||
| Ground | Ghost | 7 | 3 | 2 | |
| Ground | Dark | 7 | 5 | 1 | |
| Rock | Ghost | 6 | 4 | 1 | |
| Ghost | Fire | 6 | 5 | 1 | |
| Ghost | Ice | 6 | 5 | 1 | |
| Fighting | Ice | 6 | 6 | 1 | |
| Fire | Dark | 6 | 7 | 0 | |
| Ice | Dark | 6 | 7 | 0 | |
| Fighting | Electric | 6 | 7 | 2 | |
| Ground | Fairy | 5 | 2 | 1 | |
| Ground | Dragon | 5 | 2 | 2 | |
| Ground | Ice | 5 | 3 | 1 | |
| Flying | Ghost | 5 | 4 | 1 | |
| Ghost | Water | 5 | 4 | 1 | |
| Fighting | Dragon | 5 | 4 | 2 | (did not pass the Restrictive Criterion) |
| Fighting | Flying | 5 | 5 | 1 | |
| Ghost | Steel | 5 | 5 | 1 | |
| Fire | Psychic | 5 | 5 | 1 | |
| Water | Psychic | 5 | 5 | 1 | |
| Water | Dark | 5 | 6 | 0 | |
| Ghost | Grass | 5 | 8 | 1 | |
| Grass | Dark | 5 | 10 | 0 | |
| Ghost | Fairy | 4 | 3 | 1 | |
| Flying | Water | 4 | 4 | 0 | |
| Water | Fairy | 4 | 4 | 0 | |
| Ground | Bug | 4 | 4 | 1 | (did not pass the Restrictive Criterion) |
| Ghost | Electric | 4 | 4 | 2 | |
| Flying | Dark | 4 | 5 | 0 | |
| Electric | Fairy | 4 | 5 | 1 | |
| Electric | Psychic | 4 | 5 | 2 | |
| Steel | Dark | 4 | 6 | 0 | |
| Electric | Dark | 4 | 6 | 1 | |
| Bug | Water | 4 | 8 | 0 | |
| Flying | Ground | 3 | 0 | 1 | |
| Ghost | Psychic | 3 | 1 | 2 | (did not pass the Restrictive Criterion) |
| Normal | Ground | 3 | 2 | 2 | |
| Ghost | Dragon | 3 | 2 | 2 | |
| Fire | Dragon | 3 | 3 | 1 | |
| Water | Dragon | 3 | 3 | 1 | |
| Dragon | Dark | 3 | 3 | 1 | (did not pass the Restrictive Criterion) |
| Poison | Ground | 3 | 3 | 2 | |
| Dark | Fairy | 3 | 4 | 0 | |
| Fighting | Ghost | 3 | 4 | 2 | |
| Poison | Ghost | 3 | 4 | 2 | |
| Poison | Psychic | 3 | 4 | 2 | (did not pass the Restrictive Criterion) |
| Normal | Fighting | 3 | 5 | 1 | (did not pass the Restrictive Criterion) |
| Poison | Electric | 3 | 5 | 2 | (did not pass the Restrictive Criterion) |
| Bug | Electric | 3 | 8 | 1 | |
| Psychic | Dark | 2 | 2 | 1 | (did not pass the Restrictive Criterion) |
| Electric | Dragon | 2 | 3 | 2 | |
| Normal | Water | 2 | 4 | 1 | |
| Poison | Water | 2 | 4 | 1 | |
| Poison | Dragon | 2 | 4 | 2 | (did not pass the Restrictive Criterion) |
| Poison | Dark | 2 | 5 | 1 | |
| Normal | Electric | 2 | 5 | 2 | |
| Normal | Ghost | 1 | 3 | 2 | |
| Normal | Dark | 1 | 5 | 1 |