diff --git a/packages/pokemon/src/__tests__/evMapping.test.ts b/packages/pokemon/src/__tests__/evMapping.test.ts
new file mode 100644
index 000000000..74deb8442
--- /dev/null
+++ b/packages/pokemon/src/__tests__/evMapping.test.ts
@@ -0,0 +1,39 @@
+import { describe, test, expect } from 'bun:test'
+import { getEVForTool, DEFAULT_EV_MAPPING, MAX_EV_PER_STAT, MAX_EV_TOTAL } from '../data/evMapping'
+
+describe('getEVForTool', () => {
+	test('returns EV mapping for known tools', () => {
+		const bashEV = getEVForTool('Bash')
+		expect(bashEV).toBeDefined()
+		expect(bashEV!.attack).toBe(2)
+		expect(bashEV!.speed).toBe(1)
+	})
+
+	test('returns undefined for unknown tools', () => {
+		expect(getEVForTool('UnknownTool')).toBeUndefined()
+	})
+
+	test('all mapped tools have correct stat shape', () => {
+		for (const [, ev] of Object.entries(DEFAULT_EV_MAPPING)) {
+			expect(ev.hp).toBeDefined()
+			expect(ev.attack).toBeDefined()
+			expect(ev.defense).toBeDefined()
+			expect(ev.spAtk).toBeDefined()
+			expect(ev.spDef).toBeDefined()
+			expect(ev.speed).toBeDefined()
+			// EVs should sum to > 0
+			const total = ev.hp + ev.attack + ev.defense + ev.spAtk + ev.spDef + ev.speed
+			expect(total).toBeGreaterThan(0)
+		}
+	})
+})
+
+describe('EV constants', () => {
+	test('MAX_EV_PER_STAT is 252', () => {
+		expect(MAX_EV_PER_STAT).toBe(252)
+	})
+
+	test('MAX_EV_TOTAL is 510', () => {
+		expect(MAX_EV_TOTAL).toBe(510)
+	})
+})
diff --git a/packages/pokemon/src/__tests__/fallback.test.ts b/packages/pokemon/src/__tests__/fallback.test.ts
new file mode 100644
index 000000000..95f3b581b
--- /dev/null
+++ b/packages/pokemon/src/__tests__/fallback.test.ts
@@ -0,0 +1,28 @@
+import { describe, test, expect } from 'bun:test'
+import { getFallbackSprite } from '../sprites/fallback'
+import { ALL_SPECIES_IDS } from '../types'
+
+describe('getFallbackSprite', () => {
+	test('returns 5 lines for every species', () => {
+		for (const id of ALL_SPECIES_IDS) {
+			const sprite = getFallbackSprite(id)
+			expect(sprite.length).toBe(5)
+		}
+	})
+
+	test('returns pikachu fallback for unknown species', () => {
+		const sprite = getFallbackSprite('unknown' as any)
+		expect(sprite).toEqual(getFallbackSprite('pikachu'))
+	})
+
+	test('each line has consistent width', () => {
+		for (const id of ALL_SPECIES_IDS) {
+			const sprite = getFallbackSprite(id)
+			const widths = sprite.map(line => line.length)
+			// All lines should be roughly the same width
+			const maxWidth = Math.max(...widths)
+			const minWidth = Math.min(...widths)
+			expect(maxWidth - minWidth).toBeLessThanOrEqual(2)
+		}
+	})
+})
diff --git a/packages/pokemon/src/__tests__/names.test.ts b/packages/pokemon/src/__tests__/names.test.ts
new file mode 100644
index 000000000..fe224e899
--- /dev/null
+++ b/packages/pokemon/src/__tests__/names.test.ts
@@ -0,0 +1,44 @@
+import { describe, test, expect } from 'bun:test'
+import { SPECIES_NAMES, SPECIES_I18N, SPECIES_PERSONALITY } from '../data/names'
+import { ALL_SPECIES_IDS } from '../types'
+
+describe('SPECIES_NAMES', () => {
+	test('has name for every species', () => {
+		for (const id of ALL_SPECIES_IDS) {
+			expect(SPECIES_NAMES[id]).toBeTruthy()
+		}
+	})
+
+	test('Charmander name is correct', () => {
+		expect(SPECIES_NAMES.charmander).toBe('Charmander')
+	})
+})
+
+describe('SPECIES_I18N', () => {
+	test('has i18n for every species', () => {
+		for (const id of ALL_SPECIES_IDS) {
+			expect(SPECIES_I18N[id]).toBeTruthy()
+			expect(SPECIES_I18N[id]!.en).toBeTruthy()
+		}
+	})
+
+	test('has Chinese translations', () => {
+		expect(SPECIES_I18N.pikachu!.zh).toBe('皮卡丘')
+		expect(SPECIES_I18N.squirtle!.zh).toBe('杰尼龟')
+	})
+})
+
+describe('SPECIES_PERSONALITY', () => {
+	test('has personality for every species', () => {
+		for (const id of ALL_SPECIES_IDS) {
+			expect(SPECIES_PERSONALITY[id]).toBeTruthy()
+		}
+	})
+
+	test('personality is non-empty string', () => {
+		for (const id of ALL_SPECIES_IDS) {
+			expect(typeof SPECIES_PERSONALITY[id]).toBe('string')
+			expect(SPECIES_PERSONALITY[id]!.length).toBeGreaterThan(0)
+		}
+	})
+})
diff --git a/packages/pokemon/src/__tests__/pkmn.test.ts b/packages/pokemon/src/__tests__/pkmn.test.ts
new file mode 100644
index 000000000..73f0e788d
--- /dev/null
+++ b/packages/pokemon/src/__tests__/pkmn.test.ts
@@ -0,0 +1,56 @@
+import { describe, test, expect } from 'bun:test'
+import { FROM_DEX_STAT, TO_DEX_STAT, mapBaseStats, mapGenderRatio, getPrimaryAbility } from '../data/pkmn'
+
+describe('FROM_DEX_STAT', () => {
+	test('maps all 6 stats', () => {
+		expect(FROM_DEX_STAT.hp).toBe('hp')
+		expect(FROM_DEX_STAT.atk).toBe('attack')
+		expect(FROM_DEX_STAT.def).toBe('defense')
+		expect(FROM_DEX_STAT.spa).toBe('spAtk')
+		expect(FROM_DEX_STAT.spd).toBe('spDef')
+		expect(FROM_DEX_STAT.spe).toBe('speed')
+	})
+})
+
+describe('TO_DEX_STAT', () => {
+	test('reverse maps all 6 stats', () => {
+		expect(TO_DEX_STAT.hp).toBe('hp')
+		expect(TO_DEX_STAT.attack).toBe('atk')
+		expect(TO_DEX_STAT.defense).toBe('def')
+		expect(TO_DEX_STAT.spAtk).toBe('spa')
+		expect(TO_DEX_STAT.spDef).toBe('spd')
+		expect(TO_DEX_STAT.speed).toBe('spe')
+	})
+})
+
+describe('mapBaseStats', () => {
+	test('converts Dex stat format to our format', () => {
+		const result = mapBaseStats({ hp: 45, atk: 49, def: 49, spa: 65, spd: 65, spe: 45 })
+		expect(result).toEqual({
+			hp: 45, attack: 49, defense: 49,
+			spAtk: 65, spDef: 65, speed: 45,
+		})
+	})
+})
+
+describe('mapGenderRatio', () => {
+	test('returns -1 for genderless', () => {
+		expect(mapGenderRatio(undefined)).toBe(-1)
+		expect(mapGenderRatio('N')).toBe(-1)
+	})
+
+	test('calculates female ratio', () => {
+		expect(mapGenderRatio({ M: 0.875, F: 0.125 })).toBe(1) // 12.5% F → 1
+		expect(mapGenderRatio({ M: 0.5, F: 0.5 })).toBe(4)    // 50% F → 4
+	})
+})
+
+describe('getPrimaryAbility', () => {
+	test('returns first ability', () => {
+		expect(getPrimaryAbility({ '0': 'Overgrow', '1': 'Chlorophyll' })).toBe('overgrow')
+	})
+
+	test('returns empty string for missing ability', () => {
+		expect(getPrimaryAbility({})).toBe('')
+	})
+})
diff --git a/packages/pokemon/src/__tests__/species.test.ts b/packages/pokemon/src/__tests__/species.test.ts
new file mode 100644
index 000000000..e6ea5db6e
--- /dev/null
+++ b/packages/pokemon/src/__tests__/species.test.ts
@@ -0,0 +1,69 @@
+import { describe, test, expect } from 'bun:test'
+import { getSpeciesData, getAllSpeciesData, DEX_TO_SPECIES } from '../data/species'
+import { ALL_SPECIES_IDS } from '../types'
+import type { SpeciesId } from '../types'
+
+describe('getSpeciesData', () => {
+	test('returns valid data for charmander', () => {
+		const data = getSpeciesData('charmander')
+		expect(data.id).toBe('charmander')
+		expect(data.name).toBe('Charmander')
+		expect(data.dexNumber).toBe(4)
+		expect(data.growthRate).toBe('medium-slow')
+		expect(data.captureRate).toBe(45)
+		expect(data.flavorText).toBeTruthy()
+	})
+
+	test('returns valid data for pikachu', () => {
+		const data = getSpeciesData('pikachu')
+		expect(data.id).toBe('pikachu')
+		expect(data.dexNumber).toBe(25)
+		expect(data.growthRate).toBe('medium-fast')
+	})
+
+	test('has baseStats with all 6 stats', () => {
+		const data = getSpeciesData('bulbasaur')
+		expect(data.baseStats).toHaveProperty('hp')
+		expect(data.baseStats).toHaveProperty('attack')
+		expect(data.baseStats).toHaveProperty('defense')
+		expect(data.baseStats).toHaveProperty('spAtk')
+		expect(data.baseStats).toHaveProperty('spDef')
+		expect(data.baseStats).toHaveProperty('speed')
+	})
+
+	test('has types array', () => {
+		const data = getSpeciesData('squirtle')
+		expect(data.types.length).toBeGreaterThan(0)
+		expect(data.types[0]).toBe('water')
+	})
+
+	test('has evolutionChain for species with evolutions', () => {
+		const data = getSpeciesData('charmander')
+		expect(data.evolutionChain).toBeDefined()
+		expect(data.evolutionChain?.[0]?.into).toBe('charmeleon')
+	})
+
+	test('has no evolutionChain for final evolutions', () => {
+		const data = getSpeciesData('charizard')
+		expect(data.evolutionChain).toBeUndefined()
+	})
+})
+
+describe('getAllSpeciesData', () => {
+	test('returns data for all species', () => {
+		const all = getAllSpeciesData()
+		for (const id of ALL_SPECIES_IDS) {
+			expect(all[id]).toBeDefined()
+			expect(all[id]!.id).toBe(id)
+		}
+	})
+})
+
+describe('DEX_TO_SPECIES', () => {
+	test('maps dex numbers correctly', () => {
+		expect(DEX_TO_SPECIES[1]).toBe('bulbasaur')
+		expect(DEX_TO_SPECIES[4]).toBe('charmander')
+		expect(DEX_TO_SPECIES[7]).toBe('squirtle')
+		expect(DEX_TO_SPECIES[25]).toBe('pikachu')
+	})
+})
diff --git a/packages/pokemon/src/__tests__/xpTable.test.ts b/packages/pokemon/src/__tests__/xpTable.test.ts
new file mode 100644
index 000000000..5b422e4f5
--- /dev/null
+++ b/packages/pokemon/src/__tests__/xpTable.test.ts
@@ -0,0 +1,64 @@
+import { describe, test, expect } from 'bun:test'
+import { xpForLevel, levelFromXp, xpToNextLevel } from '../data/xpTable'
+
+describe('xpForLevel', () => {
+	test('returns 0 for level 1', () => {
+		expect(xpForLevel(1, 'medium-fast')).toBe(0)
+	})
+
+	test('returns 0 for level 0', () => {
+		expect(xpForLevel(0, 'medium-fast')).toBe(0)
+	})
+
+	test('medium-fast: level 5 = 125 XP', () => {
+		expect(xpForLevel(5, 'medium-fast')).toBe(125)
+	})
+
+	test('medium-fast: level 10 = 1000 XP', () => {
+		expect(xpForLevel(10, 'medium-fast')).toBe(1000)
+	})
+
+	test('slow: level 5 = 156 XP', () => {
+		expect(xpForLevel(5, 'slow')).toBe(156)
+	})
+
+	test('fast: level 5 = 100 XP', () => {
+		expect(xpForLevel(5, 'fast')).toBe(100)
+	})
+})
+
+describe('levelFromXp', () => {
+	test('returns 1 for 0 XP', () => {
+		expect(levelFromXp(0, 'medium-fast')).toBe(1)
+	})
+
+	test('returns 5 for 125 XP medium-fast', () => {
+		expect(levelFromXp(125, 'medium-fast')).toBe(5)
+	})
+
+	test('caps at 100', () => {
+		expect(levelFromXp(999999999, 'medium-fast')).toBe(100)
+	})
+
+	test('roundtrip: xpForLevel then levelFromXp', () => {
+		for (let lv = 1; lv <= 100; lv += 10) {
+			const xp = xpForLevel(lv, 'medium-fast')
+			expect(levelFromXp(xp, 'medium-fast')).toBe(lv)
+		}
+	})
+})
+
+describe('xpToNextLevel', () => {
+	test('returns 0 at level 100', () => {
+		expect(xpToNextLevel(100, 0, 'medium-fast')).toBe(0)
+	})
+
+	test('returns difference to next level', () => {
+		// Level 5 medium-fast: xpForLevel(5)=125, xpForLevel(6)=216
+		expect(xpToNextLevel(5, 125, 'medium-fast')).toBe(216 - 125)
+	})
+
+	test('returns full next level XP from 0', () => {
+		expect(xpToNextLevel(1, 0, 'medium-fast')).toBe(8) // 2^3=8
+	})
+})
diff --git a/packages/pokemon/src/battle/engine.ts b/packages/pokemon/src/battle/engine.ts
index 742cd8838..f1c6b9109 100644
--- a/packages/pokemon/src/battle/engine.ts
+++ b/packages/pokemon/src/battle/engine.ts
@@ -3,7 +3,7 @@ import { Dex } from '@pkmn/sim'
 import type { Creature, SpeciesId } from '../types'
 import { TO_DEX_STAT, FROM_DEX_STAT } from '../data/pkmn'
 import { STAT_NAMES } from '../types'
-import type { BattleState, BattlePokemon, BattleEvent, BattleResult, PlayerAction, MoveOption, StatusCondition } from './types'
+import type { BattleState, BattlePokemon, BattleEvent, PlayerAction, StatusCondition } from './types'
 import { chooseAIMove } from './ai'
 
 // ─── Adapter: Creature → Showdown Set ───
@@ -45,13 +45,23 @@ function wildPokemonToSetString(speciesId: SpeciesId, level: number): string {
 	return [species.name, `Level: ${level}`, `Ability: ${ability}`, ...moves.map(m => `- ${m}`)].join('\n')
 }
 
-function getSpeciesMoves(speciesId: string, level: number): string[] {
-	// Use @pkmn/sim move pool - get natural level-up moves
-	// This is a simplified approach for the sim
+function getSpeciesMoves(speciesId: string, _level: number): string[] {
+	// In @pkmn/sim, Dex.species doesn't expose learnsets directly.
+	// Use common moves that exist in the sim's data for basic battles.
+	// The actual move pool is resolved by the Battle engine during construction.
 	const species = Dex.species.get(speciesId)
 	if (!species) return ['Tackle']
-	// For sim battles, just return basic moves
-	return ['Tackle', 'Splash']
+	// Use type-appropriate basic moves as fallback
+	const type = species.types[0]?.toLowerCase() ?? 'normal'
+	const basicMoves: Record<string, string[]> = {
+		normal: ['Tackle', 'Scratch'],
+		fire: ['Ember', 'FireSpin'],
+		water: ['WaterGun', 'Bubble'],
+		grass: ['VineWhip', 'RazorLeaf'],
+		electric: ['ThunderShock', 'Spark'],
+		poison: ['PoisonSting', 'Smog'],
+	}
+	return basicMoves[type] ?? ['Tackle', 'Scratch']
 }
 
 // ─── State Projection ───