Okay, I have gotten these three trophies, and below, I will describe the best location to undertake each trophy:
Hang Glider (Grab onto a hawk for 30 seconds)
Go to B4 of the map, and stand upon a protruding cliff (white stone compared to the rest of the ground), just nearby the dead colossal tree, a temple and a cave. Refer to this video for the exact location, after you reach there.
Wait for the hawk to fly over you, and immediately jump and hold R1. Do not let go until 30 seconds have elapsed. Other hawks in other locations often tend to bring you close to the ground, ending the ride before 30 seconds are up. There may also be other ideal hawks for this trophy, but this one is guaranteed at least. You should have maybe 3-5 stamina upgrades from glowing lizards, just in case.
Slippery Ride (Grab onto a fish for 30 seconds)
Go to C3 of the map, and there, you will see a big lake. Simply swim around until a fish goes close near you to the surface of the lake, and grab it immediately by holding R1. Do not let go until 30 seconds have elapsed. A fairly easy trophy to obtain. You should have maybe 3-5 stamina upgrades from glowing lizards, just in case.
Agro Circus (Perform all stunts with Agro)
I have not gotten this trophy yet, despite doing all possible stunts I could think out of my head with Agro. Below are the moves I did so far, and if you have anything to add to this stunt list, post here!
EDIT: I have finally obtained this trophy. Corrections are added below:
- Ride standing up (While galloping, hold R1 and press Up)
- Hang from the left side (While galloping, hold R1 and then Triangle, and press Left)
- Hang from the right side (While galloping, hold R1 and then Triangle, and press Right)
- Abrupt stop (While galloping, press Down followed by X)
- Fast gallop (While stationary, press Down + X at the same time)
- 180 degree turn (While galloping, press Down followed by X, and then Down + X at the same time)
- Firing an arrow while standing on Agro (While galloping, hold R1 and press Up; equip the bow and shoot)
- Focusing your sword's light while standing on Agro (As above, equip the sword and focus its light)
- Jump from Agro's back (Simply jump from Agro while galloping)
- Get Agro to make a jump (Simply gallop towards a cliff or ledge edge, and Agro will automatically jump)
- Pet Agro while weaponless; both on Agro and standing beside him/her, by pressing the Circle button