For keepaways, the best way to deal with them is to superjump and block. If you have a dash, you can super jump and move forward. If you have a character like X-23, you can use the air slashes to move around. If you have assists that have some kind of beam, use the beam, jump and dash to cover yourself.
If they're using ground arrows, you can jump and avoid it. If he's either jumping or using the up arrows, you could try wave dashing in. If they're using assists, you better pray that you have another assist that can cover you as well.
Try not to pushblock TOO much against projectiles since you want to save as much time to close yourself in.
Task with a good assist is a pain, and even once you get in, he actually has tools to deal with you. The thing is, his arrows have a lot of holes once you get used to them, so you just gotta pick and choose. What I end up doing is wait until Task jumps, call ironman assist (because I'm assuming he's gonna be calling an assist to cover) and depending on the character, do different things. If I'm running X-23, I super jump and air slash, if I'm running deadpool, I'd teleport. Again, if Task does super in the air, my assist is going to end up eating a super, so it's really a game of chance.
Sometimes I wave dash in and end up eating a spidey swing. It really depends what I feel like.