In the Grand Finale, the three core Ninja Storm rangers taking on Lothor and winning... WITHOUT THEIR POWERS! ...Well, they used their ninja powers, but it was still cool.
Shane: We might not be Power Rangers, but we've still got POWER!
Cam dueling Lothor as part of the latter's Start of Darkness. It's a really impressive unmorphed fight and one of the best in the series.
Heck with that- it's one of the best in the entire franchise.
Tori taking on the five evil versions of her friends in The Wild Wipeout. Even though she was losing (and badly), I still think this was one of her biggest Crowning Moment of Awesome (and Tori had a few) mainly because no one took them on until she did.
Cam taking on Lothor in the Grand finale. The glasses came off, he got up and opened up a can of whoop ass.
It happened in the Power Rangers Dino Thunder team-up, but this troper always found the Brainwashed and Crazy one-on-one fights between the Ninja Storm and Dino Thunder main threes to be awesomely badass. I watched Dino Thunder for Tommy, and I watched Ninja Storm because that entire two-parter made the characters look like paragons of awesome and silly. Ninja Storm is easily my favorite season.
Zurgane, who really needed to be let out of the bag more often. Remember how thoroughly he trashed the then-three Rangers in Thunder Strangers, part one (or was it two?) and then all six in General Deception?