Which laptop is most preferable for creating ue4 games for mobile and what specifications needed?
There’s a number of factors to consider, largely your budget and how involved in game development you see yourself being, but you can find a list of recommended hardware requirements on the Epic wiki here- Hardware Requirements.
This laptop was recommended by a number of UE4 users in the forums a while back- I’m sure you could probably find something better now but that should give you a good baseline of the specifications you should be looking for in a laptop that can handle whatever the engine throws at it.
If you’re only interested in simple arcade style mobile games you could get away with a fair bit less, but I’d encourage you to look down the road a bit and future proof your purchase. As you get more experienced with the Engine you’re probably going to want to take advantage of the more processor and GPU intensive features that ship with Unreal, which will be a frustrating experience if you go too cheap.
As a starting point you want to avoid any laptop that doesn’t have a dedicated graphics card, and want a processor running at 2.5 GHz at a minimum. You also don’t want to settle for less than 8GB of RAM but I’d recommend going higher if your budget allows it.
My last recommendation would be to reconsider the prospect of choosing a laptop over a desktop for game development. If space restrictions at home are an issue or if you expect to be working on the move a lot then that’s fine and you’ll be able to find a laptop up to the task, but if you’re planning on spending a lot of time with Unreal then a larger screen with an external mouse and keyboard will make your life much easier, and your time using Unreal much more enjoyable.
I hope that helps!