Answers for furry-furret
There are 100 floors in Western Cave. On the 100th, you do battle Mewtwo. You do not have to clear Western Cave to get the other birds. My advice: Put a friend bow on your leader and use dragon-type moves to kill the birds. (I have a level 100 Articuno that can take out an entire room in one hit with Powder Snow. My regular attack does 250+) And, your team is okay. I would suggest learning a new move other than scratch, though.
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