Attacks » Hurricane
If I use Castform's "Hurricane" attack and I have no benched Pokemon, do I have to discard an Energy card?
No, if you have no Benched Pokemon all Energy remains attached to Castform.
Source: Brilliant Stars FAQ; TPCi Rules Team (2022-02-24)
Attacks » Hurricane
If I have only Special Energies attached (no Basic Energy) and use Tornadus' "Hurricane" attack, do I have to discard an energy or what?
If you don't have any Basic Energy cards attached to Tornadus, you simply ignore that part of the Hurricane attack.
Source: PUI Rules Team (2011-11-03)
Attacks » Hurricane
If I have no Benched Pokemon and attack with Tornadus' "Hurricane", do I have to discard an energy?
No. If you have no Benched Pokemon there is no place to move an energy card, so you would not do that part of the attack.
Source: Emerging Powers FAQ (2011-09-01), PUI Rules Team (2011-09-01)