I couldn't get that one to work. i had to destroy the pirates before he was able to be seen with the visor...
anyways, use plasma on the ice caps of the pirate (1 charge shot destorys 1). then after all 4 are gone, pirates will be summoned. usually multiple of the same color. destory them with easy 1 hit combo shots (super missile, wavebuster, ice spreader, flame thrower) then switch to power beam (if there is at least 1 of these guys, save him for last) then charge that weapon up turn on that x ray visor spot him, and nail with a super missile. the time i beat him was about a 1/2 hour.. it takes work to destory the extra pirates and be able to find the big dude. usually you can get 2-3 super missiles off and leaving him with 1 or 2 hits left. then just repeat. if he summons the ice dudes, you may not beable to defeat them in time. usually if you just dodge the attacks then you shouldn't be taking lots of damage. hope that helps you out.