I assume scizor has technician? I'm not a fan of the choice band, but I guess that depends on your battle style, considering he only has 2 attacks it may work.

No offense, but the focus sash is a whore item. I guess it's fair game for wi-fi or whatever, but my friends and I ban it when we play. Substitute seems to be kind of pointless too, I think Alakazam would benefit more from Calm Mind or another attack. I'd go with Psyshock in case of SpDef tanks or Energy Ball to cover more weaknesses, but if you're going to use a focus sash, Hyper Beam might be a good move to have when you have 1 hp left and want to go out with a bang.

Toxic orb Breloom is awesome, and I'm digging the moveset

Typically double items are banned in OU, so you'll need to swap out the Leftovers for something else on one of them. I'd say go with the choice band on Jellicent since it has one attack anyways, then go with something else on Scizor, like a Shell Bell, or a Steel Gem. The berry that reduces damage from a fire attack could be a good choice too.

I'm not a fan of Jellicent in general, but it's not a bad pokemon. I'd get rid of taunt for an attack, but that's just me, if you keep taunt, I hope your Jellicent has cursed body.

Blissey looks good

For Forretress, I don't really understand the point of the Shed Shell. You could go with one of the EV-training items (like the macho brace) to halve his speed and up the power of Gyro Ball. Also, having both spikes seems sort of redundant and one rapid spinner ruins it all (so high-risk/high-reward i guess), I'd pick one of them and get Explosion or Earthquake (the latter choice being if you really are worried about a Magnezone trapping you)

Give the Scizor Leftovers.

And before you say "That's too many Leftovers," THERE IS NO SUCH THING.

Hell yeah

choice band + roost/Swordsdance is a major suicide, because your opponent gets a free turn he could use to switch in a frail sweeper without getting it damaged
focus sash together with substitute doesnt make much sense either

does your blissey have serene grace?

breed it and teach it tribeam, ull have a 60% chance of either par frz or brn
and blisseys sp attack is average soo

as long as the baby has serene grace anyway

Sounds good though i prefer toxic and seismic toss for the reliability

this is true. i like what u did with ur alakazam and breloom by the way