Will Rare Candy be Nerfed with BW Release Even Though it ISN"T in the Set?
Yes, it and Great Ball, Defender and Unown (TR-51) have Errata issued on them, even though they are not included in the BW expansion set:
http://www.pokemon.com/us/news/tcg_bw1_rulechanges-2011-04-11/
Errata
The following cards now have new official text, some of which is very different from previous versions. When using the following cards, always use this text to determine their effects:
Rare Candy
Choose 1 of your Basic Pokémon in play. If you have a Stage 2 card in your hand that evolves from that Pokémon, put that card on the Basic Pokémon. (This counts as evolving that Pokémon.) You can't use this card during your first turn or on a Basic Pokémon that was put into play this turn.
Changes: It can't be used on your first turn, and it can't be used on a Pokémon played this turn.
Potion
Heal 30 damage from 1 of your Pokémon.
Changes: Heals 30 damage instead of 20 damage.
Great Ball
Look at the top 7 cards of your deck. You may reveal a Pokémon you find there and put it into your hand. Shuffle the other cards back into your deck.
Changes: This card works very differently now, it can no longer search the entire deck for a Pokémon and put it directly onto Bench.
PlusPower
During this turn, your Pokémon's attacks do 10 more damage to the Active Pokémon (before applying Weakness and Resistance).
Changes: This card no longer attaches to a Pokémon when used.
Defender (HS—Undaunted, 72/90)
Attach Defender to 1 of your Pokémon. Discard this card at the end of your opponent’s next turn. Any damage done to the Pokémon Defender is attached to by attacks is reduced by 20 (after applying Weakness and Resistance).
Defender protects against all attacks, even ones not made by the opponent.
Unown (HS—Triumphant, 51/102)
Poké-Power CURE
Once during your turn, when you put Unown from your hand onto your Bench, you may remove all Special Conditions from your Active Pokémon.
Use of this Poké-Power is optional.