: U FIREBALLS ARE 2 SLOW!
: You shielded/jumped one Fireball? Have another.
Nope, no Luigi will ever get bored of spamming Fireballs. You jump over them? Have a floating Fireball. You shield? Get grabbed. You spotdodge? Cyclone'd. You PS? Have another to PS while I slowly make my way to you and Cyclone you to the face once I'm close enough.
Luigi's Fireballs are very strong projectiles. Hell, even more than your own arrows or Mario's own Fireballs. They have very low commitment, deals 5% (6% at midrange), incredibly low end lag, they float, and basically create a fiery wall if the Luigi player wants to.
And I know what people might think, but Guardian Orbitars are rather slow to execute, so even if you can reflect one, he'll cancel it with another, and you won't gain any benefit from it anyway.
Don't do it at midrange. His dashing speed is slow enough to not be able too punish you if you do it far enough. Or do a jumping arrow, like Xacer said.