If the Broken Time-Space stadium is in play, can I use Rare Candy on a Basic Pokemon that just came into play this turn?
No, the wording of Rare Candy specifically says "you can't use this card during your first turn or on a Basic Pokémon that was put into play this turn". Broken Time-Space does not allow you to override that.
Source: PUI Rules Team (2011-06-09)
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)
Can I play Rare Candy on a Basic Pokémon to evolve it into a Stage 1 even though that Pokémon could evolve that turn normally?
No, this is no longer permissible [per BW rules changes].
Source: PUI Rules Team (2006-01-05), TPCi Announcement (2011-04-11), TPCi Announcement (2011-05-05)
Can I use Rare Candy on [my] first turn of a game (when Pokémon are not normally allowed to evolve)?
No, this is no longer permissible [per BW rules changes].
Source: PUI Rules Team (2004-07-22), TPCi Announcement (2011-04-11), TPCi Announcement (2011-05-05)
If you use Rare Candy to evolve a Pokémon, and the evo card has a "Coming into Play" Pokémon Power (such as Dark Crobat), does that coming into play power get activated?
Using Powers, Attacks, or Trainers that let you put a Pokémon in the game from your hand will allow coming into play Powers to activate. This is a reversal from previous rulings.
Source: PUI Rules Team (2003-10-23), PUI Rules Team (2005-04-14)
What does "This counts as evolving that Pokémon" mean, in game terms?
It counts towards the one evolution per turn for that Pokémon (with exceptions for Trainers and Pokémon Powers that break that rule) and removes Special Conditions on that Pokémon.
Source: PUI Rules Team (2003-09-26)
If I have Ditto with "Transform" in play this turn, on my next turn can I put a Basic Pokemon from my hand on top of Ditto and then immediately evolve it into a Stage 1 or use Rare Candy to evolve it to Stage 2?
Yes, you can. Ditto says "Any cards attached to this Pokemon, damage counters, Special Conditions, turns in play, and any other effects remain on the new Pokemon"; so as long as Ditto has been in play for more than a turn it satisfies the evolutionary requirement, and the Basic Pokemon card placed on Ditto can be evolved or used with Rare Candy immediately.
Source: Boundaries Crossed FAQ (2012-11-08), TPCi Rules Team (2012-11-08)
If I use Rare Candy to play Galarian Obstagoon, can I use its "Untamed Shout" Ability to place 3 damage counters on my opponent's Pokemon?
Yes, because it is still being played from your hand.
Source: Sword & Shield FAQ (2020-01-24), TPCi Rules Team (2020-02-06)
Can I use Rare Candy to evolve a Basic Pokemon into a Stage 2 Pokemon with the "Delta Evolution" Ancient Trait on my first turn or on the Basic Pokemon's first turn in play?
No, you may not.
Source: Roaring Skies FAQ (2015-05-07), TPCi Rules Team (2015-05-07)