Sailormoon:

In this season we get our introduction to BSSM and a thorough development of the history behind the characters. Usagi discovers her friends, discovers her true love, discovers her past and banishes the Dark Kingdom permanently.

Sailormoon R:

Usagi & Co. are bak, only this time they can't remember their pasts or anything that's happened since the demise of the Dark Kingdom. Everything is going fairly well until *KAPOW!* Aliens attack. So, we get our first taste of the empty filler episodes known as.. the Makaiju series. Of course, once THAT part of the story is done we're attacked by Usagi's future (i.e. Chibi-Usa and 30th century Crystal Tokyo). On the plus side we get to meet Dark Lady!

Sailormoon S:

2 mysterious Senshi keep turning up whenever the bad guys do to peer into miscellaneous people's heart crystals and return them. The senshi turn out to be Sailors Uranus & Neptune, who're trying to find the 3 talisman in order to stop the coming of the dreaded Pharaoh 90. Later on we meet Mistress 9 (who rAwKz!) and Sailor Saturn (senshi of destruction).

Sailormoon SuperS:

Now that the senshi are battling as a united front, they're doing fairly well. And then Chibi-Usa crashes their party and comes bak in time to undergo training as the newest addition, Sailor Chibi-Moon. In the meantime the bad guys of the day (Zirconia, the Amazon Trio, the Amazoness Quartet, Queen Nephirina) are searching for Helios in the dream mirrors of the general populus. Chibi-Moon gets a boyfriend (Helios) and the senshi have a heck of a time trying to keep things under control.

Sailormoon SuperStars:

So, Mamoru goes away and Usagi's kinda bummed, but she goes about fighting the weird bad guys that show up anyway. In the meantime, 3 more senshi show up along with evil senshi who don't seem to be fighting for the same things that Sailor Moon, etc. are. The 3 who do turn out to somewhat help them end up being the Starlight Senshi. In this season there's a huge showdown at the end between the senshi of the universe (Sailor Galaxia) and Sailor Moon.