A mass crossover between Sailor Moon/ Negima! Magister Negi Magi /Ranma 1/2/Harry Potter/Charmed, with quite a bit of timeline fudging to all fix together. Sailor Pluto doesn't get sealed in the time gates at the fall of the silver millennium and decides to have back up plans and forces (seems to be common sense to me), she leaks some SM magic out which leads to magic users, and multiple forms of magic. Later she forms a combined mundane/magical company called "The Tranquillity Trust: Providing peace of mind for clients with special situations". About ten years before the sailor scouts are born she goes to a bar to celebrate everything being ready, she drinks a little much and ends up in bed with one Genma Saotome. I'm nicking some ideas from other fanfiction's "Return" by josh temple, "heir to the empire" by ozzallos.
Sailor Moon timeline starts in the year 2010, inner scouts & moon are born 1996, outer's 1994 & Saturn 1998.
Ranma is born 1986, and will not follow timeline. Due to Ranma's bindings to Pluto and therefore the time gates s/he is much better at pure martial arts than in cannon (see Pluto effect for more info).
The events of Negima! Magister Negi Magi occur in 2000 onwards.
The events of Harry Potter occur 1990-1997 and are totally cannon, it is unlikely that any HP characters cross into this fic, I just want the magic from it. That is Harry's first year is in 1990 rather than the cannon 1991.
The events of Charmed occur 2005-2013 and are almost totally cannon until 2010 (season 5), after Chris arrived and is mostly trusted, the sister decide to double check. They find a summoning spell in the book of shadows for a "Lady Time: the Guardian of the timeline" and try to summon her, they miss and summon Ranma instead.
Taking from "heir to the empire" by Ozzallos, the Silver Millennium Kingdom/Queendom/Empire (SME) is an interstellar empire that uses advance technology or techno magic. Still debating whether or not to have Tenchi characters/places added in or not (please suggest).
The Pluto effect: because of the innate connection of Pluto to the time gates and Pluto to the plutonian royal family, the family members (blood members only) have a time sense. This does three things:
Gives them an internal clock more accurate than an atomic clock that is accurate no matter where they are.
A sense of if someone is meddling in time, that is to say travelling in it, stopping it or speeding it up.
A slight precognitive factor on a subconscious level, with training in martial arts this causes near perfect reactions in combat.