Several ways to appoarch it... an easy opponent.
First of all, Solidus' attacks can be easily predicted. You can see his moves from miles away, and there is not reason why Dante couldn't just dodge them.

Well, what should I say? Dodge, counter attack, dodge, counter attack... Solidus makes himself vunlerable after every of his attack. Any style, devilarm, and firearm will work just fine. Though, with Royal Guard, Dante will completely destroy him without taking a scratch. (As oppose to just destroy him without taking a scratch)

If you want me to be more specific, then Rebellion + Beowulf, Ebony&Ivory + Spiral with Royal Guard. Jump to avoid the ground sweep, (or simply keep himself out of the range) walk or quick roll to avoid missile, Air Hike or Quick roll to avoid other attacks. Just-Defense if a hit closes it while in the middle of an attack. Release/Just Release when fully charged, and DT explosion whenever possible.