How to unlock Azelf
Getting Azelf 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 Azelf works out to about 0.0146% per draw. The 70-pull pity counter guarantees a 5★, but it does not target Azelf specifically, so a guarantee can still resolve to another 5★. A duplicate Azelf refunds 300 coins at the 5★ rate.
Azelf stats and rank
Azelf carries 104 HP, 126 speed, a ×1.39 attack multiplier, ×1.39 physical, ×1.39 special, 70 defense and 70 special defense, 580 in total. On the three-stat percentile this is 80.8 out of 100, which puts Azelf at rank 69 of 966 and in tier S. What separates it from its neighbours is shape, not size: its strongest slot is speed (94th percentile) and its weakest is defense (51st percentile), so it is a specialist rather than an all-rounder.
Best moves in Azelf's pool
At move level 5 the pool is led by Body Slam at 75.6 damage per 0.71s (147.5 effective DPS, ×1.39 multiplier), then Tackle at 33.6 damage per 0.38s (124.5 effective DPS, ×1.39 multiplier), then Quick Attack at 44.8 damage per 0.56s (110.7 effective DPS, ×1.39 multiplier). 6 of its 13 damaging moves scale with the physical multiplier and 7 with the special one, alongside 4 support moves. Its physical and special multipliers are identical at ×1.39, so the pool decides the build. The top option beats the second by 22.9 DPS, which decides slot one and leaves slot two as a judgement call.
Evolution cards for Azelf
Its starting move, Confusion, evolves into Psyshock once the move is at level 5 and you hold the Reflexes card, which boosts cooldown for that run. If Reflexes never appears in that run's level-up offers, the move stays at level 5 and unevolved. 13 of its 17 moves carry an evolution card, across 6 distinct cards (Vigor, Sprint, Power, Reflexes, Armor and Magnet). The strongest of them is Body Slam at 147.5 effective DPS, so that is the one worth holding a card for first.
Azelf compared to similar partners
The two closest stat lines in the roster are Tornadus (+2 HP, -1 speed, same attack multiplier, +0 total) and Thundurus (+2 HP, -1 speed, same attack multiplier, +0 total). Against Tornadus, Azelf is 1 speed faster and the two carry an identical ×1.39 attack multiplier, and the rank gap is 16 places. Those differences are what you actually trade when swapping partners, not a straight upgrade path, so neither side is a strict upgrade and the move pools have to break the tie.