Our “play the card as printed” rule means that Base Set DCE is not considered a special energy because, unlike every other special energy card, it does not say “special energy” on it. This contradicts a WotC ruling that states otherwise: DCE is considered a Special Energy even though it isn't written on the card. (May 2, 2002 WotC Chat, Q141)

There does not appear to be any general rule in the Pokémon TCG which says that all energies that are not basic energies are special energies.

This ruling also applies to Base Set Electrode when it uses its Pokémon Power to become an energy card. While Electrode doesn’t state that it is not a basic energy like DCE does, it also doesn’t state that it is a basic energy, so it is in the same energy type limbo as DCE: Not a basic energy card, not a special energy card, just an energy card.