Recommended Training Locations

Levels 1-20
Florea Town Dungeon [Normal Type]

Tropical Path [Grass/Normal Type] [7 Floors]

Lily Pool [Water/Ground] [7F Midpoint] [15 Floors]

Levels 21-30
Garuga Quarry [Fighting Type] [11 Floors]

Lumberworks [Bug/Grass/Flying Type]

Levels 30-40
Lumberworks [Bug/Grass/Flying Type]

Sapphire Sea [Water Type]

Desolate Mountain [Bug and Steel/Dragon] [40 floor rest]

Levels 40-50
Sunlight Lake [Fire Type] [21 Floors]

Sapphire Sea [Water Type]

Desolate Mountain [Bug and Steel/Dragon] [40 floor rest]

Levels 51-70
Desolate Mountain [Bug and Steel/Dragon] [40 floor rest]

Mt. Metallurgy [Steel/Rock] [40 Floor rest] [60 Floors]

Mee Jive [Bug/Grass]

Thunderous Cloudtops [Flying/Dragon] *

Dream Forest [Grass/Fairy]

Levels 70+
Mee Jive [Bug/Grass]

Thunderous Cloudtops [Flying/Dragon] *

Florea Town Dungeon
Consists of only normal types and primarily beginner/baby pokemon like Zigzagoon, Rattata, Happiny, and Eevee. Though most of its pokemon are not recruitable. Contains a wealth of supplies, worth running if you need to restock on berries or ethers.

Lily Pool
Contains almost entirely water types with a notable amount of water/ground types. The first half is 7 floors and in the 2-7 Lvl range, so feel free to speed past that into the second half which has Lvls 10-13~. Also has Feebas at a negative base RR so bring a high level pokemon if you're worried about shinies.

Desolate Mountain
A dungeon with solid spawn rates. The first 20-40 floors are suitable for pokemon in the 30-40 range depending on type. While the later floors after the rest stop are better for pokemon 50+. Most of the pokemon until the 20s are bug type, after the layout change more varieties of types spawn including Jolteon. After the rest stop most pokemon are dragon, steel, or rock type and around level 50-55.

Sapphire Sea
An excellent training location due to both fairly high spawn rates and high initial floor spawns. Pokemon with AoE moves, and/or Water Absorb/Storm Drain will perform well in this dungeon. Just be mindful of Storm Drain on Shellos, Lightning Rod on Goldeen, various ice type moves, and Flamethrower on Octillery in later floors

Thunderous Cloudtops
Bring at least two people. Use of mobile scarves is recommended if you aren't training a ghost/flying type.