Hello, very new to unreal but I was wondering. Where to I start on how to get intense interaction from players and NCPs such as throwing, grabbing,playing,dancing, combos,sqauds, counters for others and attacking.
I would also like to use a stance system such as friendly, hostile or neutral. I want to be able to control what happens to you, allies and enemies, depending on your stance. Gonna be a power ranger mmo but just need help on getting started. Are there any blueprints that I can use/ make to have the AI grab you/ pick you up? or them giving you a piggy back? 
As far as I know there are no blueprints for that around, but it’s a good start when you take a look at some AI tutorials, after that you will know how to create what you want: v=evYE7tfWXUYhttps?v=EhYja8vwTq0
?v=VAAHKNoIg0w 
Is there a way to make AI/Players able to interact with other players and NPCs? Such as picking players up, grappling?
Yes. You can attach Actors to other Actors.
For two-party interactions, you can either have the “pitcher” (initiator) attach the “catcher” (the acted-upon actor) using some socket, or you can create a third actor, which has sockets for each of the two actors, and attach them both to that “Framework.”
Which one you choose depends on a lot of details.
The Unreal Engine animation system, and actor composition system, easily supports all the kinds of things you’re suggesting above. However, you have to actually “make it happen” through your own set of blueprints and animation components, which is a lot of work.
Start watching the various tutorials, and have fun!
You can do such stuff in different ways. Either with sockets (like mentioned) or you just push the around with an “impulse” (radial force/impulse node) or you could use a combination of everything (e.g an ik system so that the hands of the player are at the right position + sockets so that you can attach it +…) -> https://docs.unrealengine/latest/INT/Engine/Animation/IKSetups/index.html