Hello! I'm quite new here, and I got into competitive battling quite recently. These are all 'Mons that I either wish to train or already have, and I kinda decided to try making a rain team with these guys. I've been testing this team on Showdown for quite a while and I'm looking for ways to improve them before actually breeding/training them. A lot of their EV spreads/movesets were taken from some entries on the Smogon forums/elsewhere online with minor adjustments.
Without further ado...here are the members.
Sabrina (Milotic) (F) @ Damp Rock
Ability: Marvel Scale
EV Spread: 248 HP/252 Defense/8 Speed
Bold Nature
-Scald
-Rain Dance
-Ice Beam
-Dragon Pulse
Milotic is my Rain Dance user for this team. She's quite defensive and fast, and can set up a quick Rain Dance before switching out. She's also got good Special Attack, so she can hit pretty well too. She's pretty much the corner stone of this team.
Zexion (Noivern) (M) @ Life Orb
Ability: Infiltrator
EV Spread: 4 HP/252 Sp. Atk/252 Speed
Timid Nature
-Dark Pulse
-Hurricane
-Psychic
-Air Slash
Noivern is useful if I need a fast special sweeper. He knows Hurricane, which always hits in the rain, which is useful when defending the team from Fighting or Ground types. The rest of his moves are really just there for type coverage, but they work well with Life Orb and his high special attack.
Lilith (Umbreon) (F) @ Leftovers
Ability: Synchronize
EV Spread: 252 HP/4 Defense/252 Sp. Def.
Calm Nature
-Wish
-Foul Play
-Heal Bell
-Protect
I was using a BW set for Umbreon here, but I've tested her and it seems to work quite well. She can take out physical attackers (with the exception of fighting types) with Foul Play and heal herself and other members with Wish/Heal Bell, and she has Protect to endure most 2HKOs while gaining health with Leftovers. Her high defenses let her endure most attacks, which is pretty much the main reason for her being on my team.
Tatiana (Jellicent) (F) @ Leftovers
Ability: Water Absorb
EV Spread: 252 HP/220 Defense/36 Sp. Def
Bold Nature
-Will O'Wisp
-Recover
-Shadow Ball
-Surf
Jellicent is here to make use of the rain boost with Surf and get rid of most threats. Her defenses let her survive some Electric attacks and give her some time to hit back. Will O'Wisp is used to burn enemies in order to deal a little damage to them between turns.
Erik (Heliolisk) (M) @ Leftovers
Ability: Dry Skin
EV Spread: 4 HP/252 Sp. Atk/252 Speed
Timid Nature
-Thunder
-Surf
-Volt Switch
-Toxic
Dry Skin + Leftovers in the rain gives Heliolisk a lot of health every turn, which is why I really like using him on my team. Rain-boosted Thunder and Surf and high Special Attack and Speed make Heliolisk quite the force to be reckoned with. It's quite fun and useful in the rain.
Latula (Scizor) (F) @ Scizorite
Ability: Technician
EV Spread: 252 HP/252 Attack/4 Sp. Def
Adamant Nature
-Bullet Punch
-X-Scissor
-Aerial Ace
-Swords Dance
My stock Mega-Evolution and the only reason this team is OU. Scizor is protected from most Fire attacks in the rain, and priority Bullet Punch is always good for taking out opponents that have already been damaged. The power boosts from Mega Evolution and Swords Dance definitely help her deal some pretty decent damage.
Thanks for taking the time to read through this and give suggestions! I'm still quite new to competitive battling, and help is always appreciated! :)
Without further ado...here are the members.

Sabrina (Milotic) (F) @ Damp Rock
Ability: Marvel Scale
EV Spread: 248 HP/252 Defense/8 Speed
Bold Nature
-Scald
-Rain Dance
-Ice Beam
-Dragon Pulse
Milotic is my Rain Dance user for this team. She's quite defensive and fast, and can set up a quick Rain Dance before switching out. She's also got good Special Attack, so she can hit pretty well too. She's pretty much the corner stone of this team.

Zexion (Noivern) (M) @ Life Orb
Ability: Infiltrator
EV Spread: 4 HP/252 Sp. Atk/252 Speed
Timid Nature
-Dark Pulse
-Hurricane
-Psychic
-Air Slash
Noivern is useful if I need a fast special sweeper. He knows Hurricane, which always hits in the rain, which is useful when defending the team from Fighting or Ground types. The rest of his moves are really just there for type coverage, but they work well with Life Orb and his high special attack.

Lilith (Umbreon) (F) @ Leftovers
Ability: Synchronize
EV Spread: 252 HP/4 Defense/252 Sp. Def.
Calm Nature
-Wish
-Foul Play
-Heal Bell
-Protect
I was using a BW set for Umbreon here, but I've tested her and it seems to work quite well. She can take out physical attackers (with the exception of fighting types) with Foul Play and heal herself and other members with Wish/Heal Bell, and she has Protect to endure most 2HKOs while gaining health with Leftovers. Her high defenses let her endure most attacks, which is pretty much the main reason for her being on my team.

Tatiana (Jellicent) (F) @ Leftovers
Ability: Water Absorb
EV Spread: 252 HP/220 Defense/36 Sp. Def
Bold Nature
-Will O'Wisp
-Recover
-Shadow Ball
-Surf
Jellicent is here to make use of the rain boost with Surf and get rid of most threats. Her defenses let her survive some Electric attacks and give her some time to hit back. Will O'Wisp is used to burn enemies in order to deal a little damage to them between turns.

Erik (Heliolisk) (M) @ Leftovers
Ability: Dry Skin
EV Spread: 4 HP/252 Sp. Atk/252 Speed
Timid Nature
-Thunder
-Surf
-Volt Switch
-Toxic
Dry Skin + Leftovers in the rain gives Heliolisk a lot of health every turn, which is why I really like using him on my team. Rain-boosted Thunder and Surf and high Special Attack and Speed make Heliolisk quite the force to be reckoned with. It's quite fun and useful in the rain.

Latula (Scizor) (F) @ Scizorite
Ability: Technician
EV Spread: 252 HP/252 Attack/4 Sp. Def
Adamant Nature
-Bullet Punch
-X-Scissor
-Aerial Ace
-Swords Dance
My stock Mega-Evolution and the only reason this team is OU. Scizor is protected from most Fire attacks in the rain, and priority Bullet Punch is always good for taking out opponents that have already been damaged. The power boosts from Mega Evolution and Swords Dance definitely help her deal some pretty decent damage.
Thanks for taking the time to read through this and give suggestions! I'm still quite new to competitive battling, and help is always appreciated! :)