If an attack would KO a Pokemon, can you use Sitrus Berry to heal it first?
No. KO's have to be resolved before the end of the turn, and Sitrus Berry heals at the end of the turn after KO's have been evaluated.
Source: TPCi Rules Team (2020-02-06)
The wording of Quick Ball is now as follows, "You can play this card only if you discard another card from your hand. Search your deck for a Basic Pokémon, reveal it, and put it into your hand. Then, shuffle your deck."
Source: TPCi Announcement (2020-01-09), TPCi Rules Team (2020-01-09)
The wording of Hyper Potion is now as follows, "Heal 120 damage from 1 of your Pokémon that has at least 2 Energy attached. If you healed any damage in this way, discard 2 Energy from it."
Source: TPCi Announcement (2020-01-09), TPCi Rules Team (2020-01-09)
The wording of Lum Berry is now as follows, "At the end of each turn, if the Pokemon this card is attached to is affected by any Special Conditions, it recovers from all of them, and discard this card."
Source: TPCi Announcement (2020-01-09), TPCi Rules Team (2020-01-09)
The wording of Pal Pad is now as follows, "Shuffle up to 2 Supporter cards from your discard pile into your deck."
Source: TPCi Announcement (2020-01-09), TPCi Rules Team (2020-01-09)
In the Expanded format, there's already a rule that says you can't include Professor Sycamore and Professor Juniper in the same deck; players must choose one or the other. The same rule applies to Professor's Research, meaning it cannot be in the same deck as Professor Sycamore or Professor Juniper.
Source: TPCi Announcement (2020-01-09), TPCi Rules Team (2020-01-09)
The wording of Sitrus Berry is now as follows, "At the end of each turn, if the Pokémon this card is attached to has 3 or more damage counters on it, heal 30 damage from it and discard this card."
Source: TPCi Announcement (2020-01-09), TPCi Rules Team (2020-01-09)
Does Channeler negate the effects of Arceus & Dialga & Palkia GX's "Altered Creation GX" attack?
It depends on who is playing the Channeler. If the player who used Altered Creation GX uses Channeler then the effects are removed; the player's Pokemon no longer do +30 damage and the player does not get to take any extra prizes from the effect. However, if the player's opponent plays Channeler, then Altered Creation GX effects are not removed as they reside on the other player (who did not play Channeler).
Source: TPCi Rules Team (2020-01-09)
Can you use N's Resolve if you have no Dragon Pokemon on your Bench?
No. You have to have a Dragon Pokemon in play in order to play this card. The intention is that the main effect of the card is to attach basic Energy cards to your Benched Dragon type Pokemon, so if you don't have a Dragon type Pokemon on your Bench, you can't play the card. (You also can't play the card if you have 0 cards remaining in your deck.)
Source: TPCi Rules Team (2019-12-05)