SIMSteven made a guide for MegaMan Legends a while ago, let me pull it out and see what it says...
Alright, here's the exact text from his guide; I hope he doesn't mind me posting it here for you.
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** Boss Battle: Juno, Part 2 **
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* Juno now has switched to a much bigger body. His attacks are a bit *
* easier to avoid, and he's a bit slower, but his attacks have some more *
* power to them. His first attack is a multiple jump attack. He'll try to *
* jump right on top of MegaMan twice in a row and the jump to the center of *
* the room and swipe the area in front of him. Just move sideways and *
* blast him on his third jump. His next attack is ground swipe attack that *
* makes straight line explosions. Jump and you should always avoid this *
* one. Another simple attack of his is a dash attack. With Juno's big *
* body, it'll be harder to avoid than his previous flying dash attack *
* because of his large size. Still, moving sideways should be sufficient *
* enough to avoid it. His last main attack is his altered version of his *
* old Power Fist attack. Juno will create a large ball and throw it at *
* you. This part is easy to avoid. The trouble is that after he throws *
* it, if Juno touches it with his next attack, it'll explode much like his *
* ground-sweeping-with-explosions attack. The tactics you used in this *
* battle should be the same as the last. Keep moving sideways and *
* continuously fire your Buster. Use your special weapons whenever you see *
* an open shot. After doing significant damage, he'll bust out his *
* ultimate attack. You'll know when he pulls it off because it looks like *
* he just exploded. A shockwave will burst after he bursts, and then he *
* will shoot ten energy beams from the sky. You'll have to run like mad to *
* avoid all of them. Look for an open path and run along until the attack *
* is over. Then, resume firing at Juno. *
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He made a really good guide, actually. If you need anymore help you can view SIMSteven's guide
HERE.