I would say its a pretty good team, very tanky, a little slow, but hits very hard. There is one very serious counter to your team: u-turn Mienshao. Fighting types will destroy most of your team, and a Gliscor/Jellicent counter to fighting isnt bad, but Mienshao will dead outrun both of them. With u-turn it has a supereffective move against Jellicent, and it can escape Gliscor's acrobat and get some damage in. There are a few more possible counters to your team, but Mienshao is OU, so I would consider it your biggest threat.
Priority moves are your best friend here, because Mienshao is very squishy. Lucario has one, but you may want to consider giving your Gliscor a Choice Scarf just to make sure he gets a flying move in. Of course, this means you will have to change your Gliscor quite a bit, so its something you will have to think about.
Also, remember that fling/toxic orb only works if they don't have an item already.
