Pokéball reference (incomplete)
For simplicity's sake, only tag if an actual pokéball is in the image.
Small pokéballs on a trainer's belt count, spherical pokéballs used as collar tags count.
Additional pokéball tags:

• apricorn_ball
• beast_ball
• cherish_ball
• clone_ball
• crystal_pokéball
• dive_ball
• dream_ball
• dusk_ball
• fast_ball
• friend_ball
• green_pokeball
• gs_ball
• heal_ball
• heavy_ball
• lake_ball
• level_ball
• lure_ball
• moon_ball
• nest_ball
• net_ball
• park_ball
• repeat_ball
• safari_ball
• team_magma_ball
• team_rocket_ball
• timer_ball
• typing_ball