i beat the game but i never had to use chaos unison. its rly complicated to me.
what you do is get in a battle and pick a dark chip and if you have the six souls u can only use them when you charge a shot make sure you trigger it when it gets big because when it is small megaman's dark soul is gonna help the virus and try to delete you. when you get to the final boss i would recommend you not to use chaos unison.

use a dark chip for union then chargeand pause. if not purple keep holding B,if it is purple release and unpause. I alwayse use ToadChaos for DarkWide without turning
dark

be careful in using dfrags(DARK CHIPS)
they might attack you...

ok i know the trick in useing that thing the only chip i know you should use for this is drk lance then click on the unitshon... what ever its spelled as then you should get a discollored mega/tomahawkman like above use purple only! if you use grenn its going to hurt cause a copy atks you... but if your in dark mode and have 1 or more hp then get hit you kinda change and it gose auto and *bam* it hurts not you thats all i know about drk chips... but what is the strongest dark chip though?

*green

and its only when you get hit and die you dont die you like switch.

choas usion