Vaporeon @ Leftovers
Ability: Water Absorb
EVs: 252 HP / 4 SpA / 252 SpD
Calm Nature
IVs: 0 Atk
- Scald
- Heal Bell / Roar / Toxic / Baton Pass
- Wish / Toxic
- Protect / Toxic
Vaporeon @ Choice Specs
Ability: Water Absorb
EVs: 132 HP / 252 SpA / 124 Spe
Modest Nature
IVs: 0 Atk
- Hydro Pump / Scald
- Scald / Surf
- Ice Beam
- Baton Pass
Vaporeon would be a cool bulky water for NU, and the best wish passer we have now that M-Dino is dead. Defensive would be a cool stall / balance mon with access to Heal Bell, Roar, and everyone's favorite move, Scald. Water immunity is nice to deal with threats like Floatzel and Samurott. It's also really bulky, it had 130 / 60 / 95 defenses meaning it's pretty physically weak but it's a great special tank. Specs probably isn't as good as defensive is, but it's an interesting concept. Set is pretty self-explanatory, Ice Beam hits Grasses, and BP is nice for momentum, speed creep is for max speed jolly Don. 110 SpA is nothing to sleep on; that's higher than Heliolisk, which is, by the way, another mon we're probably getting. Vaporeon's biggest weaknnesses are probably it's lack of physical defense and random Bloom Doom Fires.
Jellicent @ Leftovers
Ability: Water Absorb
EVs: 252 HP / 252 Def / 4 SpD
Bold Nature
IVs: 0 Atk
- Will-O-Wisp
- Hex / Taunt
- Scald / Taunt
- Recover
Jellicent is another bulky water with some interesting capabilities. Wisp is a great move even after the burn nerf and Hex is nice in conjunction with it, and works well on T-Spikes builds and Stall. Jellicent as a whole is a neat spinblocker for hazard stacking teams because of Hex and being able to Taunt slower Defoggers. Recover is reliable recovery that many defensive mons in the depths of NU lack, so that's another benefit. Enjoy your boring spread for now because who knows what threats to prepare for. Jellicent's weaknesses are pretty exploitable, and being weak to Knock Off in particular hinders its effectiveness.
Milotic @ Leftovers
Ability: Marvel Scale
EVs: 252 HP / 252 Def / 4 SpD
Bold Nature
- Scald
- Ice Beam
- Recover
- Haze
Final bulky water, Milotic is pretty self explanatory. Scald, Ice Beam is for grasses, Recover is because reliable recovery is good, and Haze stops set-up sweepers. Marvel Scale is a neat ability because you take less physical damage if the opponent tries to status you. Overall a very solid defensive Pokemon, arguably better than the previous two mons. (this is probably a no)
Registeel @ Leftovers
Ability: Clear Body
EVs: 252 HP / 4 Def / 252 SpD
Calm Nature
- Seismic Toss
- Stealth Rock
- Toxic
- Protect
Another huge defensive threat, Registeel has a great defensive type and a nice support movepool to back it up with. It specifically forms good cores with bulky Waters, and as you've very clearly seen, we're getting some of those. SToss gets consistent damage, Rocks is good, Toxic + Protect are for stalling the opponent out. Overall a good blanket check to many mons.
Would do more analysis but I'm bored, here are some more defensive mons that you'll want to look out for:
Sableye: Prankster + Wisp
Uxie: Extremely versalite with great defenses
Shiinotic: Strength Sap and some nice resists
Guzzlord: Beastly HP stat without being passive
Pyukumuku: Unaware and a stally moveset, could also abuse Z-Purify
Gligar: Eviolite-boosted bulk, Roost, could act as a wincon (this probably won't drop either)
Aromatisse: Cleric, Wish, Taunt immune
Shuckle: Hazards
Cofagrigus: Wisp, T-Spikes, Normal and Fighting immune
Shaymin: SubSeed, amazing bulk, not passive
And we're literally just getting started...