If I use Greninja & Zoroark GX's "Dark Union GX" attack, can I put Honchkrow GX or other {D} type Evolution Pokemon GX directly onto the bench?
Yes, you can.
Source: Unbroken Bonds FAQ (2019-04-19), TPCi Rules Team (2019-05-02)
Does Dewgong's "Dual Blizzard" attack let you do 60 damage each to two separate Pokemon, or does it do 60 total damage split between the two any way I like?
It does 60 damage to each of the two Pokemon separately. And don't forget to apply Weakness & Resistance where applicable.
Source: Unbroken Bonds FAQ (2019-04-19), TPCi Rules Team (2019-05-02)
Can the {R}{R} energy used for Volcanion's "High-Heat Blast" attack count as part of the "at least 4 {R} Energy in play" bonus damage?
Yes, it can.
Source: Unbroken Bonds FAQ (2019-04-19), TPCi Rules Team (2019-05-02)
When I use one of my opponent's Pokemon's non-GX attacks with Malamar's "Hypnotic Reign", do I need to have the energy required in order to use that attack?
No you do not, but you need to do any necessary effects such as discarding Energy.
Source: Unbroken Bonds FAQ (2019-04-19), TPCi Rules Team (2019-05-02)
If I use Nihilego's "Nightcap" attack to copy my opponent's Pikachu & Zekrom GX's "Tag Bolt GX" attack, does it need 6 {L} attached or just an additional 3 {L} attached in order to get the bonus effect?
Nightcap replaces the normal amount of energy required by the opponent's attack with a single Psychic Energy cost. So for Tag Bolt GX, Nihilego would need 4 total Energy (1 to pay for Nightcap + 3 extra Lightning) to get the bonus effect.
Source: TPCi Rules Team (2019-05-02)
If I use Ditto's "Copy Anything" attack to copy one of my opponent's Tag Team GX attacks with a bonus effect for extra energy attached, do you count the extra energy starting at Energy #2, or after you take into account the "necessary Energy to use that attack"? For example, if it copies Pikachu & Zekrom GX's "Tag Bolt GX" attack, does it need 6 {L} attached or just 4 in order to get the bonus effect?
You count based on the required energy that normally has to be attached for the attack. So for Tag Bolt GX, Ditto would need 6 {L} energy attached to get the bonus effect.
Source: TPCi Rules Team (2019-04-18)
When using Hoopa GX's "Devilish Hands GX" attack, can I keep choosing a Pokemon that would already be Knocked Out by previous choices, or do I have to choose a different Pokemon once I have done enough damage to KO the first one?
You make all 6 choices before doing any damage; so if you wish, you can do more damage than you need to a Pokemon in order to knock it out.
Source: Team Up FAQ (2019-01-18), TPCi Rules Team (2019-01-31)
If my opponent has no benched Pokemon, do I do 50 damage to their active Pokemon when I use Nidoking's "Drag Off" attack?
No. Damage is only done to the "new Active Pokemon". If there is no switch, then no damage is done.
Source: Team Up FAQ (2019-01-18), TPCi Rules Team (2019-01-31)
When I use Zangoose's "Head Hunt" attack, do I have to put all Pokemon I find into my hand, or can I choose to discard some or all of them?
Since you get to choose which Pokemon to reveal, you can choose to discard some or all of them.
Source: Team Up FAQ (2019-01-18), TPCi Rules Team (2019-01-31)