Could someone post the suitable tools for ASM-Hacking please?
I am very interested in it. I want to give it a try.

ASM hacking is not about tools, but about knowledge.
You'll need to learn code in c/c++. In an intermediate level. Arrays and pointers.

I'll write an in-depth tutorial here someday. Until then you might want to go learn c++ It's always useful, not only for NSMB

Actually, I've written a custom linker script for devkitPro that does exactly that.

So, basically, you write your own code, compile it with devkitPro, and then insert it into the NSMB ROM with NSMBe.
You can make "hooks", like: everytime Mario's position is updated, run this function from my code. And then, in your func, you can do stuff to modify Mario's behavior.

but please be patient
First I have to fix lots of bugs in the linker script and NSMBe's custom code inserter. And then I'll write the tutorial, step by step.