well 1st off you should totally watch Madoka, it's an amazingly creepy take on magical girl anime. 2nd yea there are a few things that are variations I mean, they can't just 100% rip off anything, but everything from personality & color matching to their familiars to the hints at a dark ending for the girls, just so much is straight from madoka.
The familiars are just like Kyubey
Lux = Madoka - pink, short pigtails, relentlessly optimistic, ranged fighter
Janna = Homura - purple, long hair, experienced, mysterious and tired
Poppy = Sayaka - blue, takes things too serious, melee fighter
Jinx = Kyoko - red, brash, excitable, uses her powers for herself
Lulu is a bit different, her counterpart should be Mami in the anime but like I said there has to be some variation. The only other BIG variation is that in the anime Madoka ends up the most powerful (though doesn't start that way) and in the skin 'lore' Jinx is said to be the most powerful.
So like, 30% general magical girl, 70% Madoka magical girl