How to unlock Eternatus
Getting Eternatus means pulling the Galar banner and hitting its 5★ slot. The 5★ band takes 1.5% of all pulls and holds 103 partners, so one specific Eternatus works out to about 0.0146% per draw. The 70-pull pity counter guarantees a 5★, but it does not target Eternatus specifically, so a guarantee can still resolve to another 5★. A duplicate Eternatus refunds 300 coins at the 5★ rate.
Eternatus stats and rank
Eternatus carries 133 HP, 133 speed, a ×1.5 attack multiplier, ×1.17 physical, ×1.5 special, 95 defense and 95 special defense, 690 in total. On the three-stat percentile this is 97.9 out of 100, which puts Eternatus at rank 1 of 966 and in tier S. What separates it from its neighbours is shape, not size: its strongest slot is special multiplier (98th percentile) and its weakest is physical multiplier (61st percentile), so it is a specialist rather than an all-rounder.
Best moves in Eternatus's pool
At move level 5 the pool is led by Dragon Claw at 48.3 damage per 0.39s (144.9 effective DPS, ×1.17 multiplier), then Body Slam at 75.6 damage per 0.71s (124.1 effective DPS, ×1.17 multiplier), then Hyper Beam at 126.2 damage per 1.76s (107.5 effective DPS, ×1.50 multiplier). 9 of its 16 damaging moves scale with the physical multiplier and 7 with the special one, alongside 5 support moves. Its special multiplier is the higher of the two (×1.5 against ×1.17), so special moves convert better. The top option beats the second by 20.8 DPS, which decides slot one and leaves slot two as a judgement call.
Evolution cards for Eternatus
Its starting move, Sludge, evolves into Sludge Bomb once the move is at level 5 and you hold the Power card, which boosts attack for that run. Menu upgrades use a separate system and never stand in for Power. 16 of its 21 moves carry an evolution card, across 6 distinct cards (Vigor, Sprint, Power, Reflexes, Armor and Synthesis). The strongest of them is Dragon Claw at 144.9 effective DPS, so that is the one worth holding a card for first.
Eternatus compared to similar partners
The two closest stat lines in the roster are Mewtwo (-15 HP, +0 speed, +0.05 attack, -10 total) and Walking Wake (-18 HP, -9 speed, -0.11 attack, -100 total). Against Mewtwo, the two are level on speed and Mewtwo hits harder by ×0.05, and the rank gap is 1 places. Read those deltas as swap costs, because a gain on one line is usually paid for on another, so neither side is a strict upgrade and the move pools have to break the tie.