no
These games can fight with each other: Pokemon stadium 1 and 2 with red, blue, yellow, gold, silver and crystal. Red, blue and yellow can battle each other and gold, silver and crystal. Ruby, sapphire and emerald can battle with each other and firered, leafgreen, Pokemon colosseum and Pokemon xd gale of darkness. Diamond, Pearl and Platinum can battle each other and Heartgold and Soulsilver. The games that can battle each other can also trade with each other as well.
The battle of get a life
In Pokemon Blue, Red, Yellow, Silver, Gold, and Crystal, the place to trade and battle friends is to the right of Nurse Joy inside every Pokemon Center. In Pokemon Ruby, Sapphire, and Emerald, the place to trade and battle is located upstairs.
No.
No you can't catch Mewtwo in Pokemon silver, you must trade it from Pokemon yellow.
no.
You cannot get an umbreon on Pokemon Yellow as they were only introduced in Pokemon Silver and Gold and from then on. You can only get Vaporeon, Jolteon, and Flareon on Yellow.
you trade it from Pokemon red/blue or yellow
Yes.
using it in battle heals your pokemon from confusion.
Yes it can. Using the Time Capsule in Gold and Silver it's possible to trade between Red, Blue, and Yellow.
m.t silver. you can also battle red there.