"I'm only 19, I'm tryin to hustle on my own / On the spot ..." (2Pac – Still I Rise (Original Version)) | pending

“Block” not “Spot”

"That Thug Passion" (2Pac – What'z Ya Phone #) | rejected

In “Thug Passion” he says 1 party Alizé, 1 part Cristal.

"But in case you didn't / I'mma stick this whole pad full ..." (T.I. – That's All She Wrote (Alternate Eminem Verse)) | rejected

I think it’s safe to say that he didn’t say “Im'ma stick this whole pad full of sticky notes to your forehead and staple it” unless he only needed one syllable for “this whole pad full of sticky notes”.

"Hungry like a fucking younger me" (Eminem – Square Dance) | rejected

Must be a double entendre, because he was also hungry, because he had nothing to eat.

"I’m Big L, Notorious, Big Pun, Shawn Carter / Sean Combs ..." (Kanye West – GOOD Music BET Cypher) | rejected

Crooked I made a similar reference on Shady’s BET cypher.

"But take a look at Mariah, next time I inspire you to wri..." (Eminem – Cold Wind Blows) | accepted

Good explanation, but I think the first R&B-diss-song was made by R. Kelly (dissing Jay-Z?).

"Dopest Westcoaster breathing" (Eminem – BET Shady 2.0 Cypher) | rejected

He adds the word “breathin'” because he doesn’t want to disrespect any of the dead Westcoasters, like 2Pac or Nate Dogg.

"Fuck that, take drugs, rape sluts / Make fun of gay clubs..." (Eminem – Who Knew) | rejected

“Make fun of [..] men who wear make-up”:
This is what Dr. Dre was made fun of for by Suge Knight, 2Pac and Eazy-E. I guess Eminem just ignores it.

"So when they was like he got shot / I was just more like,..." (2Pac – Runnin' (Dying to Live)) | rejected

Last, but not least, the 1996 shooting, which killed him.

"So-called beef with you-know-who" (The Notorious B.I.G. – Notorious Thugs) | accepted

Also, Biggie, like many other rappers, is convinced you need to be a good enough rapper to be able to diss without naming the target.