I decided to build a team around Jellicent a few days ago after having faced one team with it on the ladder.
Jellicent is a pretty cool Pokemon, thanks to its typing and ability, it can acts as a nice spinblocker while being able to prevent the placing of Entry Hazards thanks to Taunt. I decided to opt for Hex over Scald because it allows Jellicent to 1v1 effectively Pokemon like Empoleon, Tentacruel, (non-Hidden Power Electric) Volcanion, Hippowdon or Swampert.
Next, I decided to add a great and well known core : Hydreigon + Tentacruel. Tentacruel is one of my favorite Pokemon and a great Spinner in the tier. Toxic Spikes are great and kinda hard to remove thanks to Jellicent's Ghost Type. In the other hand Taunt Dragonium Z Hydreigon is a insanely good Stallbreaker that can mess with a lot of slower Pokemon while preventing Defog.
Just like Slowbro, Hydreigon, Terrakion etc.. Steelix-Mega is one of those Pokemon that became pretty good. Thanks to its typing, Steelix-Mega can check Manectric-Mega, Aerodactyl-Mega, Raikou, Latias and the majority of Fairies in the tier while providing Stealth Rock. The spread on Lix allows it to OHKO Hydreigon after 1 Curse with Gyro Ball which is super nice considering how Hydreigon is pretty much everywhere atm.
Next we have Sylveon for Wish and Cleric support and Dragon immunity. I opt for Sylveon over Florges because it has a better physical Bulk thanks to its higher HP.
Last but not least, Scarf Latias gives some Speed to the team and a good way to Revenge Kill Pokemon like Terrakion, Kommo-o / Haxorus after 1 Dragon Dance etc.. Trick is good to bother Stall while Healing Wish gives even more utility to Latias.
The team is really solid, I actually picked #7 on the ladder with it. Hope you will like it :]