Sketch is kinda short in size next to the rest of the cast. Resizing is easier when the subject is bigger than the rest, I don't know if I could get him to be the proper size; he is a very interesting character, yes and Ilu is right, it's like making him from scratch graphically wise to get him properly designed for this game.
Trust me you will see a good mixture of well known and unknown characters in the next two seasons, some really obscure ones.
About difficulty, Edi.E is indeed kinda hard for stage 3 Boss, but his difficulty is just a placeholder as this game was getting only one demo before its release, he will have his moveset adjusted a little bit so he doesn't feel too cheap, although there are already some dudes dominating him and asking for more harder bosses ahead haha. In the final build, you should expect the dificulty to rise starting from stage 4, tho.