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: Magus
Recommended Team: Crono, Frog, and Lucca
Time Period/Location:
600 AD/Magus Castle
Hit Points:
6666 HP
EXP/Tech Points/Gold:
1500/15/3000
Main Attacks
: Fire, Ice, Shadow, or Lightning Magic Attacks, Dark Matter
Major Weaknesses:
Barrier Weakness, Masamune
Mini Guide
: After battling through the seeming endless parade of enemies in Magus Castle and his minions Slash, Flea, and Ozzie, the final showdown has arrived with Magus.  Magus is partially distracted by the coming of Lavos, but still gives you one of your toughest fights in the game.  Magus can use Fire, Lightning, Ice, and Shadow Magic, and will only reveal which type of magic is after hitting you with that type (e.g. "Barrier Change; only Fire damage" will be followed by Fire 2.)  Use Frog's Masamune to weaken Magus' Magic Defense and have Crono and Lucca use physical attacks unless Magus is weak against Lightning or Fire, respectively.  When you do about 5000 HP of Damage to Magus, he may try to cast a spell, but fail.  Heal your party because his next attack will most likely be Dark Matter, a Shadow attack that can do at least 200 damage to all of your characters.  After healing, hit Magus with all your firepower until you wipe out his 6666 HP and defeat the Blue Haired Sorcerer.   
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Characters-         #1         #2           #3
Characters-    #1         #2            #3
Characters-    #1               #2           #3
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