What generation is this?
Why does Tyrantrum have a Mild Nature when zero of its moves are Special Attacks? Use Jolly. For that matter, why are you using Tyrantrum? It's been around RU in every generation it's been in. I'm pretty sure Poison Fang is not a good move.
Blizzard is not a good move on Golisopod. Why do you invest nothing in Attack on it? Timid is just awful on Golisopod, use Jolly.
Toxapex is not an attacker, it's a staller. Put moves like Recover and Toxic on it instead of garbage like Gunk Shot and Liquidation. Scald is the only attacking move you should have, for the burn chance. And don't invest in Speed. Poison Barb is an awful competitive item anyways, opt for Black Sludge instead.
Bulldoze and Hydro Pump on Azumarill? No. Use Waterfall or Liquidation or Aqua Jet, and maybe Belly Drum instead of Bulldoze. Why a Babiri Berry? Azumarill isn't weak to Steel, so it's a waste of an item.
Diggersby's Special Attack is rubbish, and no amount of investment can salvage it. Get rid of Grass Knot. I would also say Life Orb or Choice Band is a better item.
Half of your Natures are missing, and all of the ones you do have aren't good. You also underinvest in EVs, and you waste EVs in useless stats. You have three Water types and two Dragon types, one of which isn't good in OU.
TL;DR This is an awful team, please learn more about competitive.
