Defeat 6th Colossus
As soon as the battle begins, run away from the colossus, climbing the barriers as you go. When you reach the back wall, wait for the head to lower and leap onto the beard. Climb up and stab the colossus in the head until the glyph disappears, then climb down to the left part of the monster’s back to find the second weakness.
Defeat 7th Colossus
Swim around until the colossus heads to the surface to attack you. Dodge to the left or right and grab the tail when it surfaces. Hold on until you break the surface again, then make your way to the base of the first electric spike and quickly stab the beast to deactivate the spike. Repeat for the next two spikes, then move on to the head and finish the colossus off.
Defeat 8th Colossus
Climb down to the third floor - you can stay higher if your health is enough to sustain the fall - and fire at the colossus from one of the barred windows. Then move around to where the floor is destroyed, and when the colossus is investigating your last location, shoot two of its legs. The colossus will fall to the ground. Leap down on top of its belly and stab. You’ll need to repeat this at least once.
Defeat 9th Colossus
Draw the colossus out of its cave and onto one of the geysers. When the geyser erupts, the colossus will fall to one side. Shoot both of the exposed ankles, and the beast will roll over. Go around, climb its belly, and make your way to the head.
Defeat 10th Colossus
Ride around on Agro until the colossus begins chasing you. At a full gallop, pull out your bow and hold L1 to more easily target the colossus. Shoot one of the eyes, and the beast will crash into the wall. Leap onto its back and stab the weak point. You’ll have to repeat this at least once.