Ehi Guys! Very nice stall team here!
The team seems pretty cool, there is not much to say but I have to give you some little advices here and there.
First, I'll note that Leech Seed is mainly used to harass defensive teams for restores life but Tangro has regenerator so he haven't a great need of seeds and for counter the other defense teams you have all the hazards and having Jellicent you can avoid that the opponent will use RapidSpin, in this way will assure damage to each opponent makes a switch.
So instead of seeds I advise you to enter Stun Spore
, in this way you will be able to sleep and paralyze the opponent's Pokemon, but the main reason 'cause I advise this change is to reduce dramatically the momentum of the offensive team and this will make it much easier to kill.
So between sand, hazards and switchs the opponent lost a lot of the staying.
At this point I want to make a small change to Zapdos, I advise you to enter VoltSwitch> Tbolt
, in this way you will keep, however, the electric stab but you can also create a small offensive volturnchain with Jirachi which also helps to fight the offensive team and causing further switch consequently further damage from hazard.
Last thing, I want to recommend a quick change in the jellicent's moveset.
Known that SubToxic Tentacruel could give some problem then add advise to put NightShade > Scald
, in this way always will break the substitute but you will cause even 100 HP of damage each time you use it, also will be useful to break even the substitute of Toxicrock that otherwise can wall you totally.