Lean, mean fighting machines can classify some of the bosses in Chrono Trigger, but all of them can be classified as tough.  HP counts are approximated because Lucca's Sightscope can't read bosses.  Besides a picture of the boss and recommended team to face it, you can find out its location, time period, HP, Main attacks, Major Weaknesses, and a mini guide for handling the boss.
Boss Name: Golem
Recommended Team: Crono with Lucca and Marle or Frog and Robo
Time Period/Location: 12,000 BC/Zeal Palace
Hit Points: 7000
EXP/Tech Points/Gold: 1000/35/2000
Main Attacks: Mimic, Iron Orb, Lightning 2, Fire 2, Ice 2, Shadow, Blurrp!
Major Weaknesses: Everything Works Well, Antipode
Mini Guide: Golem's HP is very misleading for you might figure it to be an easy opponent.  Golem copies every spell that you cast on him, but always does the 2nd Version of a spell.  Physical attacks are the worst, however, because his Iron Orb Attack lowers one characters HP by 1/2.  For characters, you can try a balanced (Crono, Marle, and Lucca) attack like you did against Magus or bring Robo and or Frog in there or you can throw in Ayla, but the balanced attack works a little bit better because you don't have to worry about the Iron Orb.  Antipode (or Antipode 2) works well, but make sure you have plenty of mid tonics, mid ethers, and revives for this tough boss battle. 
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Characters-    #1           #2           #3
Characters-    #1            #2         #3
Characters-    #1           #2        #3
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