Can I use Zebstrika's "Sprint" Ability if I have no cards in my hand?
Yes, since you can have a hand of zero cards you can use Sprint as long as there are cards in your deck to draw from.
Source: TPCi Rules Team (2019-03-21)
Can I use Zebstrika's "Sprint" Ability to discard my hand if there are no cards left in my deck?
No, you cannot. Discarding your hand is a cost not the effect, and you cannot use Abilities for no effect.
Source: TPCi Rules Team (2019-03-21)
Can I use Zoroark GX's "Trade" Ability to discard a card from my hand if there are no cards left in my deck?
Yes you can. The first part of Trade is to discard a card from your hand, period. Then you do as much of the rest of the Ability as you are able to.
Source: TPCi Rules Team (2019-03-21)
If I have Tapu Koko {*} and only one other Pokemon on the bench, can I use "Dance of the Ancients" to put 2 {L} Energy on that one other Benched Pokemon?
No, in this case, you can put only one {L} Energy on that Benched Pokemon. The second {L} Energy would have to go onto Tapu Koko {*}, but then gets discarded immediately anyway when Tapu Koko {*} goes to the Lost Zone.
Source: Team Up FAQ (2019-01-18), TPCi Rules Team (2019-01-31)
If I only have one {L} Energy in my discard pile, can I use Tapu Koko {*}'s "Dance of the Ancients" Ability to put it on one of my Benched Pokemon?
Yes, you would do as much as you can.
Source: Team Up FAQ (2019-01-18), TPCi Rules Team (2019-01-31)
Can I use Ninetales' "Nine Temptations" Ability if my opponent has no benched Pokemon?
Yes, you can discard 2 {R} Energy cards from your hand, and that's it.
Source: Team Up FAQ (2019-01-18), TPCi Rules Team (2019-01-31)
If I use Charizard's "Roaring Resolve" Ability with only 10hp left, does he get KO'd when I place the 2 damage counters before or after I search & attach 2 {R} Energy cards?
You must finish all the text of the Ability before checking for knockouts, so yes you would search your deck and attach {R} Energy cards before KO'ing Charizard.
Source: Team Up FAQ (2019-01-18), TPCi Rules Team (2019-01-31)
Say Ditto uses its "Transform" Ability to become a Klefki, then Klefki uses its "Wonder Lock" Ability to attach it to another Pokemon as a tool. When doing this what happens to the Ditto and Klefki cards?
The Ditto card gets discarded when Klefki is attached as a tool.
Source: TPCi Rules Team (2019-01-24)
If Klefki with the "Wonder Lock" Ability is attached to a Pokemon as a Tool card, what happens if "Silent Lab" stadium comes into play? Does "Wonder Lock" shut off and Klefki get discarded, or does it remain attached to the Pokemon?
Once Klefki is attached as a Pokemon Tool card it retains its effect even when its Ability has been disabled. Once it's attached, it is essentially treated as a Tool with that text, so shutting off its Ability doesn't matter at that point. However, if something such as Lysandre Labs is in effect, Klefki won't be discarded at the end of your opponent's turn.
Source: TPCi Rules Team (2019-01-03)