Got a Shadow Zekrom you've been scraping XL for, and it didn't come out 100%? Before you power up — 30 seconds. We simulated the entire Master top 100 to see whether that spread is fine to build.
For Shadow Zekrom, attack 15 is effectively mandatory, and the compromise line is about 15/15/14. Below is the result of running the Master top 100 through a battle simulator, plus the mirror, the same-stat rival, and best buddy. (Hundo 1-shield record: 50W 50L.)
Compromise IVs
15/15/14
At L50, at or above this the win/loss matchups match a hundo.
Build it or not — at a glance
✅
Just build · 15/15/14 or better
Win/loss matchups are effectively identical to a hundo. Just power it up.
⚠️
Conditional · around 15/15/13
You start dropping Mewtwo (Shadow) and similar. If you rarely face them (low real pick rate), it's fine to run.
❌
Don't build yet · Attack 14 or below
Shadow Zekrom always loses CMP priority to the mirror and Shadow Reshiram at attack 14. Don't build it — wait for a better one.
🔬 Full-meta sim — all 100, who you meet & beat
1-on-1 battles vs the Master League top 100, per shield. Green = win, red = loss. (Rating 500 = even; higher = more comfortable.)
50W50%50L
406
358
570
801
371
500
392
801
285
605
257
562
500
483
232
407
216
736
250
500
500
548
714
391
845
415
769
529
476
570
363
260
779
508
430
600
266
703
657
110
260
474
540
495
823
459
823
341
369
468
276
312
486
423
608
823
369
519
695
736
540
337
144
251
302
513
393
260
226
365
779
614
614
706
451
443
703
605
581
627
410
845
540
823
519
801
733
638
804
747
272
625
736
344
671
459
605
614
315
524
⭐ Best Buddy (L51) effect — newly won matchups
Opponents you newly beat once best-buddied. The result depends on whether the opponent is best-buddied too, so both cases are shown.
Opp not BB (L50) · +5W
⭐
⭐
⭐
⭐
⭐
Opp also BB (L51) · +1W
⭐
※ The mirror and same-stat rival (Shadow Reshiram) return to a tie when the opponent is best-buddied too (both L51). So Best Buddy only wins the mirror when the opponent isn't best-buddied.
Why attack 15 is mandatory — CMP
Attack decides priority. Attack 14 always loses to a same-stat rival.
vsMirror (Shadow Zekrom vs Shadow Zekrom)
Mine (atk 14) vs Foe (atk 15)
shields0
L
423
shields1
L
440
shields2
L
497
vsvs rival · Shadow Reshiram
Mine (atk 14) vs Foe (atk 15)
shields0
Tie
500
shields1
L
440
shields2
L
497
Verdict by IV spread (Master League sim)
💡 15/15/15 at the top is the perfect IV (best); rows go to lower IVs downward.
Perfect·Battle-equal= win/loss identical to a hundo (no disadvantage — just use it).
Fine= it only loses to weaker (non-top) opponents, so it's acceptable to run.
N lost= it starts losing to N strong top-10 opponents — a real disadvantage.
CMP loss= at attack 14 you always lose the mirror / same-stat rivals.
‘Matchups lost’ = opponents you newly lose to at that spread (0/1/2 shields = how many shields are used).
Master League has no CP cap, so everyone is max level. When same-species (mirror) or same-stat Pokémon fire a charged move on the same turn, the higher effective attack goes first (CMP). An attack-14 Shadow Zekrom loses that priority to an attack-15 opponent. In the sim, the attack-14 mirror came out 0-shield=loss, 1-shield=loss, 2-shield=loss. In a mirror-heavy meta, attack 15 is effectively mandatory.
Where win/loss starts to split
Down to 15/15/14, win/loss matches a hundo. Below that, at 15/15/13, you begin losing Mewtwo (Shadow) — that's the breakpoint line.
Best Buddy — depends on whether the opponent is too
Best Buddy (level +1) depends on whether the opponent is best-buddied. Against a non-best-buddied opponent (L50) you newly win 5 matchups at 1 shield; against a best-buddied one (L51), 1. Top Master legendaries are usually best-buddied, so the mirror and same-stat rivals go back to a tie when both are L51. It never hurts, but it doesn't magically win the mirror.
Note that this line moves with the meta. If usage shifts or a new Pokémon arrives, the breakpoints move and a spread that's fine today can get shaky. This analysis is for Season 28 (2026.09.08~12.01); when the season changes we re-run the full top-100 sim and update it.
⭐Best Buddy (L51) effectBB CP 4620 · L51
Best-buddying even a compromise improves every matchup and beats same-stat rivals.
Hundo record by shield count
shields 0
58W · 42L
shields 1
50W · 50L
shields 2
52W · 48L
Bottom line — attack 15 is non-negotiable (mirror CMP), compromise line 15/15/14. Based on the Season 28 (2026.09.08~12.01) meta; updated when the season changes.
FAQ
Q. Do I need a hundo Shadow Zekrom?
No. Down to 15/15/14, win/loss matchups are effectively identical to a hundo. At or above that, just power it up.
Q. Attack is 14 — can I just build it?
Not recommended. At attack 14 you lose CMP priority to the mirror and same-stat rivals — a fight that should be 50:50 becomes 0:100.
Q. How long does this hold?
It's the Season 28 (2026.09.08~12.01) meta. When the meta shifts, the breakpoints and the compromise line move, so we re-run the full top-100 sim each season and update it.
Method
BasisSeason 28 (2026.09.08~12.01)ScopeMaster League Top 100Shields0 · 1 · 2Level50 / Best Buddy 51Battle engineGBL Note Simulator (PvPoke-based)Baseline15/15/15Last calculated2026-10-10
✔ Calculated & analyzed by GBL Note
These verdicts come from simulating each spread against the entire Master League top-100 across 0/1/2-shield scenarios with the open-source PvPoke engine. If no matchup flips versus a hundo it's 'Perfect/Battle-equal'; if it only loses to weaker (non-top) opponents it's 'Fine'; once it loses to a top-10 opponent it's 'N lost' by the number of losses. Attack 14 loses mirror priority — 'CMP loss'.
