Who are the Pokemon who viably could be other types through lore, design or movesets.

Or Pokemon who have relations to types other than their own.

For Example Aquatic Pokemon that aren't Water Types.

Dratini, Dragonair, Masquerain, Anorith, Armaldo, Stunfisk, Dragalge


Another is Lance's dragon-centric team from HGSS that included Gyarados, Charizard Aerodactyl.

Stantler and Noctowl has some psychic/ghost(this less so) relation withing movesets and lore.