For a traditional wincon you can pair up 5 stall pokemons with:
CMers like slowbro, suicune, clefable, gothitelle, sableye, latias, blissey
DDers like charizard, gyarados, dragonite, altaria, ttar, zygarde
BUers like talonflame, breloom, mew
SDers like gliscor, talonflame, mew, scizor, skarmory, scolipede
Cursers like ferrothorn, snorlax, quagsire
Fast cleaners like tornadus-t, scizor, talonflame, gengar, serperior
Semistall with metagross, lopunny, diancie, (or any other good mega)
Some of them are obviously much more viable than others but it never hurts to experiment and have fun with some new crazy idea. Who knows maybe something as outlandish as curse miltank could work if you really wanted to. Anyway they all share the common stall traits of bulk, recovery, and most of them have some way of assisting in the stall archetype such as hazard control, statuses, heal bells, and useful abilities.
After choosing one I try to start outlining my weaknesses to common wallbreakers and try to build around patching up the obvious holes while still maintaining some of the stall basics like hazards and a cleric. It has become quite a task lately to wall all of the ridiculous things out there so having some sort of offensive pressure, or some speed/priority of your own, can be very nice.