I think if Grasshopper Manufacture wants to promote No More Heroes: Travis Strikes Back, then why not have the main protagonist, Travis Touchdown, appear in Super Smash Bros Ultimate.

If Bayonetta can make it into Smash then why not Travis Touchdown?
A possible moveset could revolve around Travis's beam katana and maybe have the moveset be similar to Marth's or Roy's and for Travis's final smash I'm think calling his mech Glastonbury and use the takedown move he used in his fight with Charlie MacDonald in No More Heroes 2
those are my thoughts, but what do you think?