i havent finished the song yet, i will when i'm done, but im writing kind of a grungy song, and i need a cool edgy punk one or two word title ex. Negative creep, sliver, dive, stain. And do you think if my guitarist came up with the intro chord progression and i write the rest of the song, do you think he should be included in the writing credits?
Absolutely, no matter how much he contributed to your song, he still contributed so he deserves some credit. As for a title I don't know as I havent heard your song.
yes he would be IMMEDIATELY added into the credits.

considering i have no idea of the song, meaning of the song, style of the song, tempo of the song, lyics of the song i have no idea what to name it so ill write the first word that comes to my head