Comprehensive Dialga's best counters (Machamp < 50% of time)
Machamp is the best counter to Dialga in fewer than 50% of scenarios when considering level 40 counters with Best Friends (I'm not going to run every weather combination at every friendship level or pokemon level - however I will quickly note that at level 35 Hariyama can become the best, e.g. against dragon breath/draco meteor sets he's considerably better than Machamp - however Breloom falls off hard when not maxed letting Machamp be the best far more often).
The 3 possible best counters to Dialga depending on the situation:
1. Breloom
2. Machamp
3. Groudon
(4. Hariyama)
To simplify things: since the only "best" counters are fighting/ground, the only weather worth considering are: cloudy (fighting), clear (ground), snow (Dialga's steel), wind (Dialga's Dragon), rain (Dialga's thunder), then extreme is the same as all the rest.
Cloudy:
Breloom is #1 against both thunder sets, and dragon breath/iron head.
Machamp is #1 against both Draco Meteor sets, and metal claw / iron head.
The opposite (Machamp/Breloom) is #2 in all 6 cases.
Clear:
Machamp is the best against both Draco meteor sets (with Groudon second against metal claw and Mamoswine second against dragon breath).
Groudon is the best against all other sets (with Machamp second against double steel, and Breloom second in the other 3 cases)
Snow:
Machamp is best against both Draco Meteor sets (with Hariyama second) and both Iron Head sets (Hariyama and Breloom second once each)
Breloom is best against both Thunder sets (with Machamp second both times)
Wind:
Machamp is best against both Iron Head sets (Breloom second for both)
Breloom is best against the other 4 sets (Lucario second for both Draco Meteor, and Machamp second for both Thunder sets)
Rain:
Machamp is best for both Draco Meteor sets and double steel (with Hariyama second for Draco Meteor and Breloom for steel)
Breloom is best for the other 3 sets with Machamp second
All other weather:
Same as Rain (3 each to Machamp and Breloom)
In total (giving equal weight to Clear/Cloudy/Snow/Rain/Wind/Other) that's:
#1 = Machamp 17 times
#1 = Breloom 15 times
#1 = Groudon 4 times
i.e. Machamp is the best counter 17/36 or 48.6% of the time (less than half).
The big additional point to this is that I'm going strictly based on time to win as the only entrant. This is effectively DPS, but it penalizes low-tankiness pokemon like Breloom since they need to re-enter more. However in raids with more people, re-entry is less of a problem - which should ultimately mean that Breloom doesn't need to re-enter as much and likely overtakes Machamp overall in these cases (basically every Draco Meteor set).
All results from Pokebattler.
Answers
I assume Machamp must be able to tank Draco Meteor at level 40.
Otherwise it wouldn't make sense that Machamp is always best against Draco Meteor except in the wind (where it's boosted and Breloom becomes best against it and Lucario becomes second [being able to tank it thanks to his resistance]).
What surprised me was Machamp surpassing Groudon against Draco Meteor sets in Clear Weather. Groudon obviously can tank it, but Machamp must get better DPS out of tanking it, firing off all the energy he gains from tanking it, then fainting. Groudon either just barely gets KO'd by the second DM, or frequently faints with high energy (since EQ is only 1 bar).
Didnt try PokeBattler, but in my own experience noticed, that Machamp survive Draco Meteor only, if have 90%+ HP and have 40 lvl. It was with Palkia( Dialga 5 less attack shouldnt change much) when we need just finish boss so thats why i used autoselected Machamp to rejoin. But more often Machamp will be just OHKOed so i think Breloom should be first choice vs DM sets and Thunder, and Machamp vs Iron Head.
I'm not sure why you optimize for TTW for larger groups. No matter what you do, you'll only get one or two damage balls, and since it is a large group, you're going to win the raid. When short-manning, DPS definitely matters, but an additional re-lobby isn't worth a small gain in DPS. Basically, I'm not convinced Breloom is the best choice.
