Okay, so this is how I see the MHA characters, plus my two characters, as Undertale (no the ships I have with MHA won't correspond with the ships I see in Undertale) 

Koy is Sans, 100% 

Kay is Papyrus, I dunno why but I see it 

Inko would be Toriel, just seems right 

Bakugou is Undyne, prove me wrong 

Iida is Alphys, both smart people 

Shigaraki is Flowey, both bad guys that some people like 

Toga is Chara, again, prove me wrong 

Endevor is Asgore, he or All Might maybe 

Aoyama is Mettaton, they share the same energy 

Kirishima and Tetsutetsu are the two guards with the bromance, like come on 

Mineta is Jerry, both are hated very much 

Tamaki is Nabstablook, energy is very similar 

Todoroki is Frisk, I think it seems right (tho, if I did an rp, Frisk would be you) 

Last one, Denki would be Monster Kid, energy is close

These are just the first few that came to mind