ditto
No legendary Pokemon cannot be bred
Latias is a Pokemon that was introduced after the release of Pokemon Crystal, and you cannot trade between those two games, therefore, you cannot obtain it.
You cannot find Squirtle in Pokémon Crystal.
No, Sneasel cannot evolve in Crystal.
You cannot evolve Misdreavus in Crystal.
You cannot catch Mewtwo in Pokemon Crystal, but you can trade it from a Pokemon Red or Blue. Hope this helped :)
Darkar is not a Pokemon in HeartGold. Darkrai is a Pokemon, but it cannot be bred since it is a legendary Pokemon. You cannot breed dark type Pokemon, either.
No, Mewtwo cannot be caught in Pokemon Crystal. It can, however, be traded from Pokemon Red, Blue, or Yellow.
No. Pokemon of the Undiscovered Egg Group cannot be bred.
Pokemon Crystal can be played on the Gameboy Color, the Gameboy Advanced and the Gameboy Advanced SP. Pokemon Crystal cannot be played on the original Gameboy and Gameboy Pocket.
You cannot get the TM for Ancient Power in Pokemon Crystal. Ancient Power has yet to be a TM in any of the Pokemon games.
You cannot get Cyndaquil in Pokemon Red. It is only on Pokemon Silver, Gold, and Crystal.