This is Last part of the a comprehensive analysis of how Legendaries function in Pokemon Go, within the context of the Legendary Raid meta, regular Raid meta, and Gyms in general. Using that information, you can determine which Legendary Pokemon are worthy of resource investment.
Unless they’re your favorite, and/or you’ve got more Rare Candy and dust then you know what to do with, don’t just start pouring resources into these Pokemon without thinking it over very, very, very carefully.
A bulky Water type with a respectable defensive DPS (better than Water Gun/Aqua Tail Vaporeon) that cannot be placed in gyms; adding to that, Suicune has a below average offensive DPS, unable to reliably secure type advantage with Psychic/Dark type quick moves paired with Water type charge moves. Not particularly usable on offense, and categorically unusable on defense.
Conclusion: Don’t Power Up Suicune.
The Mystic mascot is an incredibly potent Ice type attacker, in a game that has little need for an Ice type attacker at the moment. Articuno is one of the tankiest Pokemon currently available, due to its very high base 242 Defense and solid 180 base Stamina.
Articuno almost has Lapras’s bulk, and its DPS is on par with Frost Breath/Avalanche Cloyster, giving it the highest Total Damage Output for an Ice type in the game at present. But here’s the problem: we don’t have stacked towers of Dragonite anymore. You don’t need a Pokemon that can make it through multiple defending Dragonite when there can only be one in a gym at a time.
Further, Articuno has little to no use in the current raid meta. The only High-Tier Raid Pokemon you can deal SE damage to are Rhydon, Venusaur, and Zapdos (when it becomes available). Articuno risks being hit with a double SE Stone Edge (In exchange for only exploiting a single weakness – Vaporeon’s DPS and overall survivability is much better here), and Zapdos deals Electric type SE damage to Articuno.
Articuno is terribly outclassed by higher DPS counters into Venusaur. But do not despair – Articuno has the potential to be great in the future. We may get Dragonite Raids at some point, or other pseudo Legendaries from future generations may get added to the rotation (Gen III’s Salamence, Gen IV’s Garchomp, etc.). Hold onto as many as you are able to catch; just don’t invest in them quite yet.
Conclusion: Don’t Power Up Articuno Right Now.
Technically a Mythical Pokemon and not a Legendary, Mew as well as Celebi find themselves with very solid and well-rounded base stats: 210 Attack, 210 Defense, 200 HP. I previously criticized Mew for not having a STAB quick move, but now the problem is even worse.
Pound is not only non-STAB, but also not Super Effective against anything. That’s a huge detriment to its usability. Especially considering that its wide array of possible movesets shift Mew towards becoming a sub-optimal specialist for that type.
It will never deal as much Grass type damage as Exeggutor; as much Ice type damage as Articuno; as much Electric type damage as Raikou, Zapdos or Jolteon – the list goes on and on.
Regardless of what charge move you get, be it Solar Beam, Thunder, Blizzard, or even its STAB charge move Psychic, Mew is going to be a sub-optimal user of that typing. Its good base stats are completely wasted, outclassed as both a specialist and a generalist, leaving it no place in the meta other than as a souvenir from a Tier 5 raid.
Conclusion: Don’t Power Up Mew.
Another Grass/Psychic type like Exeggutor, but with considerably more bulk (Mew and Celebi are close to Rhydon) and less DPS (Confusion/Hyper Beam Celebi is about 19-20% worse than Confusion/Solar Beam Exeggutor).
Celebi’s problem is its highest DPS moveset makes it impossible to get type advantage with both fast and charge moves being SE against the same defender. Since Hyper Beam is Normal, it will never be SE against anything.
Celebi would have been great for its Grass typing, but it learns no Grass type charge moves. Its only double STAB moveset is Confusion/Psychic (overall its 2nd best neutral DPS moveset). Well that’s a huge problem, because you know who else learns Confusion/Psychic? Mewtwo. I’ll leave it to you to decide who’s worth the resource investment.
Conclusion: Don’t Power Up Celebi.