>>718014497 (OP)
>How do I beat the Tigrex?
You need to pay attention to his patterns, and exploit his AI when he turns around.
For example, if you're GS or Hammer and he charged past you, he will turn 90 degrees once, and then turn a certain amount one more time to face you. Before this happens, charge up and prepare an attack. Time it so that you hit him as he faces you, or even so you hit him after the first 90 degree turn. Be prepared to roll out of the way after, and perhaps even through his arm.
Another big opening is when he does the big leap twice. Once he leaps twice, he's going to do nothing but chomp the air for about 6 or 7 seconds and then do the slow turn around thing. Wail on his tail and back legs, and then exploit that turn animation for a few more hits, and get the fuck out of the way again. You can also get a few hits in whenever he does a spin, just make sure you're close but not TOO close in front of him.
Watch videos online, you don't need armor to hunt Tigrex in FU, just patience and skill.