Is not sure what counts as a dungeon. What would probably qualify?
Yes
Larger caves (Rock Tunnel, Reflection Cave, Terminus Cave, Cerulean Cave, Mt Moon...)
Evil team bases
Towers (Sprout Tower, Lavender City tower, Celestial Tower, Dragonspiral Tower...)
Seafoam Islands
Victory Road
Power Plant?
Abandoned Ship
Vast Poni Canyon
No
Gyms
Smaller caves (Diglett Tunnel)
Nugget Bridge (more of a gauntlet)
Hm. More or less defines it as a place difficult (or more tedious) to leave and heal. May have means to heal inside the place, however. Does not need to contain a boss.
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Liked the Abandoned Ship in Hoenn. Felt like a good, natural use of various HM moves. Seems quite unique. (Sort of forgot it existed, though. Skips by it pretty easily.)
Generally feels okay with Victory Road style dungeons. Prefers dealing with trainers (with some variation in teams) versus wild Pokemon (Geodude Geodude Geodude Zubat Zubat).
Views optional areas (Power Plant, Abandoned Ship) as forgettable, simply due to not being pushed into them. Blurs all of the Pokemon cemetery towers together too.