Trainers » Rare Candy
Can I evolve Dratini in play to Dark Dragonite by using Rare Candy?
Yes. [This is true as long as there is a normal evolutionary path between the basic and the Stage 2 "Dark" Pokémon.]
Source: PUI Rules Team (2005-02-10)

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