EDIT: Corrected effective BP due to a mistake I made; the text may be wrong but the charts are right.
Hey, sorta prototyping an analysis method, but trying to score typings based on how many mons can hit it for less than 100 BP, 150 BP, and 200 BP, those being the thresholds of "neutral EQ", "STAB EQ", "SE EQ". This is under the idea that if a mon cannot hit you with anything more than a non-stab coverage move, it probably loses to you, if it can hit you with a neutral mid-high BP stab you're probably at an advantage, and if it can hit you with a SE coverage move, or a high BP stab you probably aren't amazing into it. I did this analysis, as well as calculating the average BP across all mons, as well as the average BP, ignoring anything above 300 BP for Ground/Water. Don't worry too much about the "score" as that's just weighting based on high rank mons.
Typing 1: | Typing 2: | | |
Water | Ground | | |
Score_100 | 40 | N_100 | 7 |
Score_150 | 145.0833333 | N_150 | 33.41666667 |
Score_200 | 259 | N_200 | 64 |
Mean BP | 197.151176471 | BP_Ceil | 167.816532191 |
As ya can see, this typing walls a fair number of mons pretty hard, shoutouts to the following:
Hard Wall Eff BP <= 100 (Offensive only): Utility Cinderace

, Dragonite

, Heatran

, Astrolotl

,
Now I should note that Dnite, by virtue of using low BP moves without initial STAB, is gonna be a false positive in this analysis.
Positive Matchup BP <=150 (Offensive Only): Kingambit

, Defensive Great Tusk

, Krilowatt

, Gholdengo

, CM Valiant

, Samurott-Hisui

, Enamorus

, Hoopa-Unbound

, CB Roaring Moon

, ...
There's a lot here honestly, you can see the analysis spits out 33 mons that this typing has a postitive matchup into, in that they can't hit it super hard beyond neutral STABs. The fractions are because sometimes you check one set and not hte other. The effective BP this mon faces is also at 120, which tracks as it's often taking medium BP stabs, or resisted hits.
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Do contrast with a typing I've seen brought up in the discord a bit, Fire/Dark doesn't perform nearly as well according to these metrics.
Typing 1: | Typing 2: | | |
Fire | Dark | | |
Score_100 | 25.5 | N_100 | 6.5 |
Score_150 | 66.41666667 | N_150 | 16.91666667 |
Score_200 | 223.4166667 | N_200 | 55.41666667 |
Mean BP | 216.382827374 | BP_Ceil | 203.261622418 |
While it gets a lot of leverage out of being a very solid check into Kingambit, and being fine into Dragapult, that's lowkey where it ends. A lot of mons in the meta are carrying Earth Power, Earthquake, or Focus Blast, and those really show. The average mon has about 25 more BP when its facing Fire/Dark than Water/Ground, and while you hard wall about as many mons as Water/Ground, you have a positive matchup into far fewer. I can see this being functional, but damn if a lot of mons don't just hit it with SE EQ or SE EP in the current meta. I may edit in one more typing once I think of one, but yeah.
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Generally I'm in favor of Water/Ground, Water/Flying, and Poison/Dark.
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Edit:
Typing 1: | Typing 2: | | |
Fire | Flying | | |
Score_100 | 70.91666667 | N_100 | 17.58333333 |
Score_150 | 139.4166667 | N_150 | 32.58333333 |
Score_200 | 238 | N_200 | 59 |
Mean BP | 197.719823941 | BP_Ceil | 170.002161026 |
Fire/Flying is an interesting one cause like, so much of its strength does come down to just styling on Fire/Fairy/Ground combos, and those are honestly quite common in CAP. You have a similar number of overall positive matchups to Water/Ground, but a lot more mons that you simply just hard wall based purely on typing. This also is combined with a very generous set of STABs when looking at offensive presence. Flying is infamous for being the most clickable STAB in the game, and Fire is pretty close. That said, a lot of the moves that were slightly below 100 BP were well, Knock Off, which pretty trivially just forces you out. Overall a bit hard to analyze this one, and it shows a weakness of this analysis, that it ignores high utility moves.