If you are making this a mono water team, wynaut (lol) make it a rain team. Swampert is beast in the rain especially in mega, so here's what I suggest:
Swampert: NEVER use two stab moves unless it's for priority. Take out dig and dive and replace them for rain dance and avalanche. Avalanche hits grass types super effective, swampert's one weakness, and rain dance boosts swampert's speed to make it beast.
Ludicolo: switch icy wind for ice beam. surf and giga drain are great. Switch energy ball for rain dance, and use either rain dish or swift swim. Both are good. Have it hold a damp rock to increase the turns of rain.
Pelipper: give it rain dish for ability. Moves: hydro pump, hurricane, rain dance, and aqua ring. You will heal 1/8 health each turn and hurricane has 100% accuracy. Life orb recoil with the aqua ring and rain dish will basically remove the recoil. Yay!
Azumarill @ Big Root
Brave Nature
Ability: Huge Power
252 Attack/100 Defense/100 Special Defense/52 HP
-Play Rough (STAB)
-Aqua Tail (STAB)
-Aqua Jet (Priority)
-Aqua Ring (STAB)
Your azumarill was way too mixed, so I focused it some more.
Gyarados: Waterfall over aqua tail for chance of flinch. Dragon Dance to replace trash. Ice fang and crunch are awesome. Give it ability moxie.
Wailord: substitute over heavy slam. Hydro pump good. Aqua ring over amnesia. Rain dance over rest. Ability oblivious. Do 252 attack and 252 HP. Use the other four for anything but special attack.
Your team was kind of off, but I saw lots of potential in it. I hope you put my thoughts into consideration.
