The Vallak Dino-mech can do a ton of damage with its flame breath to anyone in its vicinity. So don't be around it! Use range on the dinosaur, firing rocket after rocket at it, and keeping range by running backwards constantly or using an SDL Jet Bike if its available in that stage. Another trick is to use the helicopter. If you get the helicopter at the right height, you can avoid the flame breath, and only have to really watch out for its flailing arms and surrounding buildings.
Bonus Waffen
Genocide Gun - schafft alle Missionen auf Inferno
PX50 Bound Shot - schafft alle Missionen auf Hardest
Y20 Impulse - schafft alle Missionen auf Hard
ZE Launcher - schafft alle Missionen auf Normal
Zero Laser Rifle - schafft alle Missionen auf Easy