- What's がよ?
If you're sure that this が is not a subject marker, then this が should be a derogatory vocative particle (see: Why is が added at the end of この小娘が?) and よ is a sentence-end particle. So Xがよ is like "Damn you, X" or something.
- What about 気合いもなにも?
~も何もない is a set phrase. See:
So the basic meaning is "this is not a matter of 気合い". Perhaps this guy wanted to say "You're way too weak physically, and just having a fighting spirit means nothing"?
EDIT: On second thought, I noticed this 気合も何もねえ could be a simple relative clause that modifies ダサ坊 (i.e., "You lame brat who doesn't even have a fighting spirit!"). See the context.