Bad Boy Entertainment
Bad
Boy Crew
All the beef was sparked by the shooting in the Manhattan Studio in New York.
Pac claimed and told an interviewer of Vibe magazine that it was setup by Biggie
(Notorious BIG) and Puffy (Sean Puffy Combs) (Puffy being the mastermind). Basically,
Pac had serious beef with Bad Boy Records and was clear to show his anger in
his lyrics - "If you wanna be down with Bad Boy, then f**k you too!.."
Notorious B.I.G. (Biggie Smalls)
They were once good friends & Pac was claimed to be the source of Biggie's
fame and riches. Tupac would do performances with BIG to assist BIG in his struggling
career to be known as a rap star. When Pac was shot in the Manhattan Studio
in NY, he claimed that Biggie was aware that the shooting would take place,
but failed to give him full information. Their friendship was later worsened
when BIG released an album that was remarkably similar to Pac's upcoming album,
which resulted in Tupac re-recording the entire new album. Pac also mentioned
that Biggie was "rapping about my life" when he was rapping about the cash,,jewelry
and assets he did not really have.
Sean "Puffy" Combs aka P. Diddy
Tupac had problems with Puffy as he believed he was the mastermind behind the
NY shooting. Other (and a more simpler) reasons was because he was down with
Bad Boy Records, and he was "fake" or unoriginal as he did not make his own
lyrics or music. Some words of retaliation include: "Puffy weaker than a f*cking
block I'm running you ni**a..." - Hitemup
Chino XL

Chino dissed many people including Whitney Houston, Eddie Murphy and of course
Tupac. In keeping up with his tradition, Tupac retaliated: "..Chino XL, f**k
you too. All you mother f**kers, f**k you too!" - Hitemup. It is believed that
Chino XL's comments was only there to create publicity and make him a well known
rapstar, but this scheme was obvious, so Tupac didn't mention his name too many
times as this would only create a name for Chino XL.
Dr. Dre
This beef started at the time of Snoops trial.
Dre never showed up, which Tupac saw as a dis to Snoop and all of Death Row.
Then there was the fact that Dre hadn't released an album since "The Chronic",
and really wasn't doing a lot, while collecting a lot of money. Tupac also said
that Dre was gay, and said that he cheated on his wife. "What's down in the
darkness, will come to light".
Toss It Up - "No longer dre day, arive derche, long and forgotten, gotten for plottin-child's play check your sexuality, as fruity as this alize quick to jump ship, punk trick, what a dumb move cross Death Row, now who you gonna run to? Like those other suckers cuz you similiar pretendin to be hard-oh my god-check your temperature, screamin Compton, but you can't return, you ain't heard brothas pissed cuz you switched and escaped to the burbs."
Jay Z

I don't know much about the specifics of how this started. But Jay-Z did have a track off of his album 'Reasonable Doubt' called "Brooklyn's Finest" featuring Notorious BIG in which Biggie makes reference to Tupac sleeping with his wife (not a diss) but also says the line "Who Shot Ya" which could be looked upon as being a reference to the 1994 NY shooting. Maybe Jay-Z's association with that song and his association with other Bad Boy artists such as Junior Mafia and Lil Kim, Puffy, and, obviously, Biggie could have led to 2Pac's disses. That's my best guess and all I have to say on the rivalry.
LL Cool J
Tupac's
beef with LL Cool J, oddly enough, was started by LL, it seems. Tupac had respect
for LL and even speaks about it in the track "Old School" from 'Me Against the
world'. LL's song "I Shot Ya" is said to be a response to Biggie's "Who Shot
Ya?" (Thought to be directed towards 2Pac, although BIG denied it) where he
apparently disses Pac. Claiming, not really but in the track, that he shot him
in the NY Shooting. Tupac responded, a little bit in his unreleased song where
he says "Nigga, I'll rock your mutha fuckin bells!!" Referring to LL's old hit
"Rock The Bells" Anyway, that's about all I know about it...
Mobb Deep

With the recording of "New York, New York" with Tha Dogg Pound on the album
titled, "Dogg Food", the heat between the two rappers was bought to light. Other
influences included the fact that Mobb Deep released a song titled "Thug Life,
we still livin' it" after he wrote an article about quitting Thug Life. Mobb
Deep was believed that he said alot of things in his music that he did not carry
out. "Oh yeah Mobb Deep, you wanna f*ck with us? You Little young a** mutha
f*ckas, don't one of you ni**as got sickle-cell or something? You f*cking with
me, ni**a ? You f*ck around and catch a seizure or a heart-attack. You better
back the f*ck up before you get smacked the f*ck up, that how we do it on our
side.." - Hitemupboy, get it right."
Nas

Tupac didnt' like the fact that Nas ripped Pac's beats such as the track for "All Eyez On Me". Pac and Nas squashed the beef after a while.
Dan Quayle
This is obviously not a rapper
like the rest of these enemies. He was the vice-president of the USA after 2Pac's
first solo album "2Pacalypse Now", and he wanted to ban the album cause of the
violent "cop-killing" lyrics, which according to him influenced people to kill
cops. He said "There's absolutely no reason for a record like this to be published"
and "It has no place in our society". Though this is not a kind of enemy that
would get in a (gun)fight with 2Pac, it might have been one of the most dangerous
ones, with his power to ban Pac's music. Fortunately he failed in doing this.