Sa-weet!
The full names of these two are:
"Kenzan Kuro Musha Ver." (Kenzan Black Warrior Ver.)
"Gekisoumaru Kuro Shishi Ver." (Gekisoumaru Black Lion Ver.)
According to the text, these are specially-coated powered up forms these two take when using the illusionary powers of the "Black Legendisc".
With a black-colored Goradora having recently shown up in the cartoon as a powered up form (despite there currently being no toy of one), I wonder if these might show up as powered up forms for these two in the show as well.