When you turn off the solid behavior of a block off, it will disable several options but I’m just looking at the friction for this. Friction should have a new role when a object is set to be a non solid and that should be to slow down anything that goes within the block. I have found it very hard to mimic this using in game behaviors. I really hope this is something that can be easily plopped into a update without too much coding.
When you make a object non solid you make it so it cant interact with the objects around it. What you can do to make an object slow down is when hitting a block is add an force not as strong as your movement force that would push back against the block you are moving through. It should totally be possible using game behaviors.
Also you can check out this incomplete game, Adventures Of an 8-Bit Ninja, I did some weird stuff with not solid enemies that you might find helpful.