The Shadow Pikachu card has 999 HP.
There is no shadow pikachu in either one of those games.
You can't get a Shadow Pikachu on Ruby/Sapphire/Emerald.
Its free if you do the glitch right. YOU beat the elite for 4 times in a row withought losing all your Pokemon. Then you goto the poke center with a pikachu in your 1st slot. goto the trading room....
Probably yes. The Issu pokédex goes up until pokémon #645, Shadow Pikachu will most likely become pokémon #666.That is all I know