How to unlock Mew
There is no direct purchase for Mew. It appears on the Kanto banner inside the 5★ pool. The 5★ band takes 1.5% of all pulls and holds 103 partners, so one specific Mew works out to about 0.0146% per draw. The 70-pull pity counter guarantees a 5★, but it does not target Mew specifically, so a guarantee can still resolve to another 5★. A duplicate Mew refunds 300 coins at the 5★ rate.
Mew stats and rank
The sheet lists Mew at 115 HP, 120 speed, ×1.25 attack, ×1.25 physical and ×1.25 special, with 100 defense and 100 special defense — 600 base-stat total. On the three-stat percentile this is 78.5 out of 100, which puts Mew at rank 87 of 966 and in tier A. Relative standing explains more than the total here: its strongest slot is HP (87th percentile) and its weakest is attack multiplier (63rd percentile), so it spreads its value fairly evenly.
Best moves in Mew's pool
At move level 5 the pool is led by Body Slam at 75.6 damage per 0.71s (132.6 effective DPS, ×1.25 multiplier), then Tackle at 33.6 damage per 0.38s (112.0 effective DPS, ×1.25 multiplier), then Quick Attack at 44.8 damage per 0.56s (99.6 effective DPS, ×1.25 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 ×1.25, so the pool decides the build. The top option beats the second by 20.6 DPS, which decides slot one and leaves slot two as a judgement call.
Evolution cards for Mew
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. That card has to drop inside the run; nothing in the permanent menu replaces it. 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 132.6 effective DPS, so that is the one worth holding a card for first.
Mew compared to similar partners
The two closest stat lines in the roster are Celebi (+0 HP, +0 speed, same attack multiplier, +0 total) and Jirachi (+0 HP, +0 speed, same attack multiplier, +0 total). Against Celebi, the two are level on speed and the two carry an identical ×1.25 attack multiplier, and the rank gap is 1 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.