Ok, let's break this down:
I run forward for a dashing attack only to get boomerang'd then fsmashed
The only thing you can really do about this is either to not dash in that way, or to short hop over them and watch for the smash. Unfortunately, MK's sword slashly harmlessly
through the boomerang, so you can't just deflect it with his sword. Your tornado or drill rush will plow right through it, though.
Fair hits then I get hit with a dair
This one's easy, but takes a bit of practice. You need to space your attacks properly. If you don't know what this means, then I'll explain. I'll make a video just about spacing in a bit since people seem to have problems with it. Tru= made a video that has some spacing explanations in it, but I can't remember where it is.
-Spams arrows, but most of time I can get it with tornados, BUT he usmashes me while in helpless
You should NOT be getting hit during the helpess part of the tornado. If you bring it up, Toon Link should be caught in it. Otherwise, keep it to the ground. If you're not going to get TL with that last hit of the Tornado (the one with knockback), then tornado away before it runs out.
Arrow spam can be a pain to get around, especially if done right (let's assume it is). If he/she is short hopping and arrows and then shooting one on the ground (and then repeating), then it can be difficult. You're basically forced to use an attack the forces through or jump over. It's situational so just try different things and see what works. The most important thing is this:
Whatever you do, try to get an understanding of how he/she will react. If you can predict a fsmash (don't forget the second hit), then you can leave them wide open for attacks of your own.
