The wording of Rare Candy is now as follows, "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." So now it can't be used on your first turn, and it can't be used on a Pokémon played this turn.
Source: TPCi Announcement (2011-04-11), PUI Rules Team (2011-05-05)

Relevant cards

Note: All applicable cards may not be listed below.
BW10_105
BW10_85
BW5_100
DP4_102
EX13_90
EX2_88
EX9_83
HGSS2_82
POP5_7
POP8_10
SM1_129
SM2_165
SM7_142
SWSH1_180
SWSH1_180
XY5_135