Pretty controversial nomination, but here we go.
Nominating Manaphy for A+
Manaphy is a very good pokemon atm. A mono water typing isn't bad defensively, while offensively it isn't too shabby either. 100 / 100 / 100 bulk is also decent. However, the true reason why manaphy is such a monster is because of its access to one of the best boosting moves in the game, tail glow. After one tail glow boost, manaphy's power reaches insane levels and this can be further boosted by a potential rain dance. TG + RD is a very effective set that easily demolishes stall teams alone and can even put in work against balanced teams if given the chance. Manaphy's ability hydration also allows it to run rest very effectively; if manaphy is in rain, rest instantly heals manaphy and it does not even fall asleep thanks to hydration. This allows manaphy to even run a mono attacking set with CM, rest, and rain dance, as it can slowly boost up with calm mind and heal itself with rest. Scald is also great as it allows manaphy to fish for burns against pokemon such as ferrothorn or chansey, weakening them so manaphy can break past them. Another cool thing about manaphy is its coverage. Ice beam can be nice to break past ferrothorn if not running rain dance, psychic allows manaphy to destroy mega venusaur, and energy ball can bop water-types such as rotom-w and slowbro. HP Fire is even an option to lure in ferrothorn and take it out quickly, and it was used by style in OST. Manaphy can easily tailor its coverage to match its teams needs. For example, if you have a metagross you can run energy ball to lure in bulky water types. Another reason why manaphy is so good is because of how well it pairs up with some very common pokemon. Pokemon such as mega metagross and mega gallade really appreciate manaphy's ability to lure in and remove bulky water-types, defeat bulky ground-types such as hippowdon and gliscor, and most importantly, beat mega sableye.
Manaphy can singlehandedly tear down stall teams thanks to its access to tail glow, allowing it to put in tons of work against stall teams and even balanced teams. CM sets are also hard to beat as it is hard to wear down thanks to rest and hydration. Manaphy's coverage is also really good and can easily be changed up to match the needs of the team. Finally, manaphy pairs up very well with some pretty common pokemon, making it a good choice on lots of teams. Manaphy is just a really solid pokemon at the moment due to the fact of how much work it can put in against stall teams making it a great partner for pokemon that have trouble with pokemon such as hippowdon, gliscor, sableye, and the like. For all these reasons, I really think manaphy deserves a rise.
I think this nom has been shot down before but i'll reiterate the reasoning:
While this thing is cool against balanced and stall, it's
absolutely crap vs offense and extremely prone to being revenge killed by just about anything.
(btw mmeta 2hko's mega sableye with mash (with sr) but anyways lol) mmeta has both thunderpunch and gknot to help it get past waters anyway, it doesn't need manaphy for that. If anything, manaphy needs mmeta to remove ferro and mvenu for it. Aka it does not singlehandedly defeat stall teams.
Now as you mentioned, it has a few coverage moves to let it deal with multiple different things. I'm going to use the term in the correct context unlike how it has been thrown around quite a bit recently and say that manaphy has 4mss.
It needs psychic to hit mvenu, which is otherwise a solid hard af counter.
Energy ball is needed to hit rotom-w, slowbro, and other waters in general
scald is scald
Ice beam is wanted to hit dragons and grasses.
and hp fire is nice to hit ferro, which none of the other options do.
note that none of these moves go past 90 base power either :< your moves are pretty weak too
Of course, you need to run tail glow alongside all of this, so ultimately there will be SOMETHING that manaphy cannot get past, even when running tail glow + 3 attacks. Of course, one mon to bring down every balanced/stall team would be pretty broken but you can begin to see that manaphy cannot do its job on its own. It's fairly independent, i won't exaggerate its cons, but it ultimately DOES still need some lure support, and ultimately DOES need a free turn to set up tail glow in the first place.
That's another whole dimension imo. You see breakers like mega diancie, mega gardevoir, mega heracross, mega medi, char-y, etc pretty much just clicking a move and watching things perish, all they need is a free switch-in. Mana requires a lot more maintenance in that you need to both get it in safely and get a turn to set up, during which stall users could be laying down the toxic necessary to come out on top in the end, the turn that other mega wallbreakers never really give. That's a huge difference.
One notable pro of the little prince is that its a wallbreaker of such quality but doesn't take up a mega slot, which is amazing for teambuilding flexibility; it lets you pick your mega to build around or to handle offense instead of using one to break stall/balance.
mana has its good points but its ultimately too weak vs offense, too easily revenged, and has zero immediate power. It should stay A.