Hello dude, never mind 
Yes, there are good game ready animations to be used, however, they are not “my game ready”
I am developing a third peson shooter in UDK/UE3, and I am use tons of mocap and game ready animations, however I had the need to edit one by one of these animations to fit in my game.
Anyway, if you purchase from Unreal Marketplace a pack with Game Ready animations already edited and fitted for UE4 Skeleton, then you can yes use them with one click, so long as all your characters use the default UE4 Skeleton, even though you can retarget the animations from one character to another in UE4 (different skeletons). But me, personally, prefeer to retarget animations from different skeletons using motion builder.
Cheers.