I agree with many of Onyx Tanuki's points, but the Rain Dance/Hydration/Rest combo is used by Manaphy very well. I agree, change to Dragon Pulse, but because of HydraRest leftovers seems unnecessary. You could have Damp Rock, or even Kee/Maranga berry to boost a defense stat.
Makes sense to me. I think Manaphy can pull it off a bit better though thanks to two factors: access to Tail Glow and its STAB. With the exception of Volcanion (whenever it gets released) and maybe Palkia, I think most Ubers pokemon are at most 2HKOed by a +3 Rain-boosted Surf, and this is coming from a BL pokemon. Goodra, on the other hand, is gonna be walled by most of the OU/UU Fairies (Florges and SpDef Diancie in particular), even if it does have room for an extra coverage move, since a lot of them are specially defensive, and its coverage move won't be running off of STAB; it could do 35% at best to fully special bulk Florges or 28% to 4 SpDef Assault Vest Florges with Sludge Wave and 41% to fully special bulk Diancie or 32% to Assault Vest Diancie with Muddy Water, while Florges' Moonblast can hit for 41% to 60%, and Diancie's can hit for 38% to 56%, depending on build and luck with min-max. I'm not saying Manaphy is without its counters and checks (again, Volcanion's gonna be a major stop if it doesn't have Energy Ball, and a fair number of pokemon it can't really safely switch in on), nor that Rain Dance/Rest/Hydration is a bad thing for Goodra (as long as your opponent isn't packing Fairy or Steel types you can hit anything at least neutrally with Dragon Pulse), just that Goodra's a bit easier to switch in on IMO.
Then again, as mentioned above, Manaphy is set in a slightly higher tier, so there's more things it'll potentially face versus what Goodra can.
Kadabra/Alakazam @ Black Sludge/Sticky Barb
Magic Guard
Timid
4 HP/Def/SpDef, 252 SpAtt, 252 Speed
- Trick
- Psychic/Psyshock
- Energy Ball/Shadow Ball/Dazzling Gleam/Knock Off
- Energy Ball/Shadow Ball/Dazzling Gleam/Knock Off
A slight twist on the classic Alakazam set. Typically you'd see this moveset on a Choice item Alakazam, allowing it to Trick its Choice item onto something like Chansey or Alomomola to keep it from being able to reliably heal the party, or with Specs, lock a physically-based opponent into a move. This version takes a bit more advantage of Magic Guard to cripple things that rely on their staying power by trading out their item for something that'll constantly damage them. While less crippling to Clerics, this can be used to hinder Assault Vest and Eviolite users considerably. Sticky Barb is the more reliable of the two, since it can damage Poison types, but you'll also have to be careful you don't hit that pokemon with a contact attack from something that's had its item Knocked Off.
Trick is, of course, to trade the damage item off, and Psychic/Psyshock for STAB depending on whether you have a lot of physical attackers on you team. From there you can go with Energy Ball, Shadow Ball, or Dazzling Gleam for additional coverage in the other two slots, depending on what you need most on your team. Knock Off is also an option if you're holding Sticky Barb, allowing Alakazam to ensure the opponent gets the Sticky Barb if you don't expect him to be able to OHKO with an attack and he has no other options open besides being foddered off.
You'll note that I set this up for either Kadabra or Alakazam. It depends on the tier you're running this set in; Alakazam is UU and up, I believe, and anything lower you'll need to default to Kadabra. The two are virtually identical in terms of use, only differing in Kadabra losing a little SpAtt and Speed. Essentially, you'll just be using Kadabra anywhere Alakazam is banned from.
Kangaskhan @ Leftovers
Scrappy
Adamant
212 HP, 252 Att, 44 Speed
- Return
- Substitute
- Wish
- Drain Punch/Power-Up Punch/Earthquake/Sucker Punch/Roar
Kangaskhan, even without its Mega Stone, is a pretty solid defensive pokemon, and this version is built to capitalize on its bulkiness. Return is STAB, of course, Substitute to block status and soak up hits, Wish for direct healing. Its HP is just high enough that with 212 EVs it can create Subs that a single Seismic Toss can't break, so you could take a few HP EVs out to beef up its Speed, or you could just go with 252 HP so it has a little extra padding. Scrappy ensures that even without Sucker Punch, Kanga isn't walled against most Ghosts.
Its final moveslot is pretty free, so there's a lot of things that would go there. Drain Punch covers Rock and Steel types, as well as providing a means to heal if Kanga gets Taunted. PuP beefs its offenses up while providing the same coverage. Earthquake provides the same anti-Rock/Steel coverage, but trades a secondary effect for power (and thankfully, the only Rock/Flying type in the NU tier, Archeops, has little enough bulk that a Return is going to eat through its resistance). Sucker Punch is good if you want to ensure the opponent is punished for attacking you directly while you wait for a Wish to drop. Roar covers you against setups and things that Substitute. Obviously these aren't your only options, and since this set runs Wish you have to keep in mind that you can't run an Egg Move on it, but these IMO are the best options. If you wish you could run Aqua Tail, Crunch, or an elemental punch for different types of coverage as your team requires. Even Seismic Toss is an option if you wanna be able to hit low HP defensive Ghosts like Dusclops, Dusknoir, or Spiritomb hard, or just want to bypass Defense. Seriously, be creative here.