How to unlock Chespin
Chespin is one of the free starters: pick it from the starter selector at the start of a run and it costs no tickets. Later copies come from the Kalos banner, where it sits in the 1★ pool. The 1★ band takes 45% of all pulls and holds 233 partners, so one specific Chespin works out to about 0.1931% per draw. The 70-pull pity counter only applies to 5★ results, so Chespin has no floor of its own and no targeted pull. A duplicate Chespin refunds 15 coins at the 1★ rate.
Chespin stats and rank
Chespin carries 95 HP, 94 speed, a ×1.04 attack multiplier, ×1.04 physical, ×0.96 special, 65 defense and 45 special defense, 313 in total. On the three-stat percentile this is 21.6 out of 100, which puts Chespin at rank 812 of 966 and in tier C. What separates it from its neighbours is shape, not size: its strongest slot is defense (44th percentile) and its weakest is special defense (16th percentile), so every one of its stats sits below the roster median, so its case rests on move pool and availability rather than raw numbers.
Best moves in Chespin's pool
At move level 5 the pool is led by Petal Blizzard at 33.6 damage per 0.26s (124.2 effective DPS, ×0.96 multiplier), then Body Slam at 75.6 damage per 0.71s (110.3 effective DPS, ×1.04 multiplier), then Tackle at 33.6 damage per 0.38s (93.2 effective DPS, ×1.04 multiplier). 8 of its 14 damaging moves scale with the physical multiplier and 6 with the special one, alongside 4 support moves. Its physical multiplier is the higher of the two (×1.04 against ×0.96), so physical moves convert better. The top option beats the second by 13.8 DPS, which decides slot one and leaves slot two as a judgement call.
Evolution cards for Chespin
Its starting move, Vine Whip, evolves into Power Whip 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. 14 of its 18 moves carry an evolution card, across 6 distinct cards (Vigor, Sprint, Power, Reflexes, Armor and Synthesis). The strongest of them is Petal Blizzard at 124.2 effective DPS, so that is the one worth holding a card for first.
Chespin compared to similar partners
The two closest stat lines in the roster are Totodile (-3 HP, +2 speed, +0.02 attack, +1 total) and Meltan (-4 HP, -2 speed, +0.02 attack, -13 total). Against Totodile, Totodile is 2 speed faster and Totodile hits harder by ×0.02, and the rank gap is 3 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.