Answer
In theory, most armies can be played alongside, it's just a question of what's sensible, possible, and if you can think of a reason for the fight.
Most Imperial forces will fight alongside one another with no issues (Imperial Guard, Space Marines, Witch Hunters, Demon Hunters) with a few exceptions.
Tyrannids will never fight alongside anyone, as they are likely to kill everyone
Dark Eldar will also rarely fight alongside anyone, expect Chaos.
Eldar often fight with most forces, and often against most forces, depending on whether it suits them or not. Orks, probably no one. They fight everything, even them selves. Tau use everyone they can get their hands on.
AnswerAt the moment, GW do not make a set of rules for matches like that, so no, 40k armies can not play FB armies.== ==
Answer All armies are legal in 5th edition.
All armies can work. Both as a rule and as a playable list.
No. The only armies in the game are Chaos or Space Marines. Being a necron player, I too wish they were in Warhammer 40k: Squad command.
Defineitley 40K.
Yes. All armies are able to beat the other armies....... there is no "Win every game" army for you to play.
Answer Warhammer Epic is much smaller than 40K. It is also cheaper.
Games Workshop made the Warhammer 40k Tabletop Game.
This rule can be found in the Warhammer 40K rulebook, but due to copyrights we are not allowed to answer this question.
This rule can be found in the Warhammer 40K rulebook, but due to copyrights we are not allowed to answer this question.
The Shred is the preferred enemy in the special rule warhammer 40k
This rule can be found in the Warhammer 40K rulebook, but due to copyrights we are not allowed to answer this question.