How to unlock Darkrai
Getting Darkrai means pulling the Sinnoh banner and hitting its 5★ slot. The 5★ band takes 1.5% of all pulls and holds 103 partners, so one specific Darkrai works out to about 0.0146% per draw. The 70-pull pity counter guarantees a 5★, but it does not target Darkrai specifically, so a guarantee can still resolve to another 5★. A duplicate Darkrai refunds 300 coins at the 5★ rate.
Darkrai stats and rank
Darkrai carries 102 HP, 130 speed, a ×1.44 attack multiplier, ×1.2 physical, ×1.44 special, 90 defense and 90 special defense, 600 in total. On the three-stat percentile this is 81.2 out of 100, which puts Darkrai at rank 67 of 966 and in tier S. What separates it from its neighbours is shape, not size: its strongest slot is special multiplier (97th percentile) and its weakest is HP (53rd percentile), so it is a specialist rather than an all-rounder.
Best moves in Darkrai's pool
At move level 5 the pool is led by Body Slam at 75.6 damage per 0.71s (127.3 effective DPS, ×1.20 multiplier), then Bite at 35.7 damage per 0.34s (126.9 effective DPS, ×1.20 multiplier), then Tackle at 33.6 damage per 0.38s (107.5 effective DPS, ×1.20 multiplier). 8 of its 12 damaging moves scale with the physical multiplier and 4 with the special one, alongside 4 support moves. Its special multiplier is the higher of the two (×1.44 against ×1.2), so special moves convert better. The top option beats the second by 0.4 DPS, which decides slot one and leaves slot two as a judgement call.
Evolution cards for Darkrai
Its starting move, Bite, evolves into Crunch once the move is at level 5 and you hold the Power card, which boosts attack for that run. That card has to drop inside the run; nothing in the permanent menu replaces it. 12 of its 16 moves carry an evolution card, across 6 distinct cards (Vigor, Sprint, Power, Reflexes, Armor and Synthesis). The strongest of them is Body Slam at 127.3 effective DPS, so that is the one worth holding a card for first.
Darkrai compared to similar partners
The two closest stat lines in the roster are Latios (+4 HP, -6 speed, -0.02 attack, +0 total) and Zapdos (+8 HP, -10 speed, -0.05 attack, -20 total). Against Latios, Darkrai is 6 speed faster and Darkrai hits harder by ×0.02, and the rank gap is 20 places. Treat the gaps as the price of the switch rather than free stats, so neither side is a strict upgrade and the move pools have to break the tie.