How to unlock Keldeo
Getting Keldeo means pulling the Unova banner and hitting its 5★ slot. The 5★ band takes 1.5% of all pulls and holds 103 partners, so one specific Keldeo works out to about 0.0146% per draw. The 70-pull pity counter guarantees a 5★, but it does not target Keldeo specifically, so a guarantee can still resolve to another 5★. A duplicate Keldeo refunds 300 coins at the 5★ rate.
Keldeo stats and rank
Keldeo carries 111 HP, 123 speed, a ×1.41 attack multiplier, ×1.1 physical, ×1.41 special, 90 defense and 90 special defense, 580 in total. On the three-stat percentile this is 88.0 out of 100, which puts Keldeo at rank 21 of 966 and in tier S. What separates it from its neighbours is shape, not size: its strongest slot is special multiplier (95th percentile) and its weakest is physical multiplier (47th percentile), so it is a specialist rather than an all-rounder.
Best moves in Keldeo's pool
At move level 5 the pool is led by Karate Chop at 46.2 damage per 0.38s (135.5 effective DPS, ×1.10 multiplier), then Body Slam at 75.6 damage per 0.71s (116.7 effective DPS, ×1.10 multiplier), then Hyper Beam at 126.2 damage per 1.76s (101.1 effective DPS, ×1.41 multiplier). 8 of its 17 damaging moves scale with the physical multiplier and 9 with the special one, alongside 5 support moves. Its special multiplier is the higher of the two (×1.41 against ×1.1), so special moves convert better. The top option beats the second by 18.8 DPS, which decides slot one and leaves slot two as a judgement call.
Evolution cards for Keldeo
Its starting move, Water Gun, evolves into Scald once the move is at level 5 and you hold the Power card, which boosts attack for that run. If Power never appears in that run's level-up offers, the move stays at level 5 and unevolved. 17 of its 22 moves carry an evolution card, across 6 distinct cards (Vigor, Sprint, Power, Reflexes, Armor and Synthesis). The strongest of them is Karate Chop at 135.5 effective DPS, so that is the one worth holding a card for first.
Keldeo compared to similar partners
The two closest stat lines in the roster are Munkidori (-1 HP, +0 speed, +0.01 attack, -25 total) and Walking Wake (+4 HP, +1 speed, -0.02 attack, +10 total). Against Munkidori, the two are level on speed and Munkidori hits harder by ×0.01, and the rank gap is 14 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.