Here are some little tips from someone who got the impossible badge.
You wanna use either No Legs with the Shooting Star, or Anna with the Razor Leaf.
Always use the One Heart Handcap( The motive is that if you take a hit with normal hp, you probably won`t take 1 Star or higher tank, as you loose 2 stages multipliers)
Use Death-Bomb, this is your friend, and is the way to keep you alive.
Use the Graze mechanic to increase your base score, some bosses turn into casual walk in the park with this(The 9-5 get`s way easier if you have a base score of 300k-400k)
Always use the base Costume, the other ones are useless.
Since you are using the One Heart Handicap, you might as well use the -15% Bullet speed, or the +15% Attack cheat.
It`s not easy, but not impossible( even though it`s the hardest impossible badge in Kongregate), most of the patterns have a easy way to deal with them, and it`s up to you to find how they work.
all people with dont know why take rank B with 100%.Is because have combo when you take 2 arrows in a little time 100% of power you take x0 next x2......its bost your poits in your next atk with 1k demage you take 2000 poits when you are on combo for exemple x10 you take 20000 in 1k demage(my max combo is 87x and oyur max combo post)