Xatu can only be found in the Area 2 of the Safari Zone.
At long last, the sixth generation does justice to the oracle bird, giving it a reasonable level-up moveset that doe not require it to go through a painstakingly high amount of levels before learning any sort of viable STAB. In addition to that, compatibility to a fairly wider array of moves than the previous games it was available in, as well as Calm Mind support starting from the seventh gym battle, have definitely made Xatu more useful than it ever was, and being outpaced by the likes of Noctowl in the Johto remakes says plenty about its former potential. In new Hoenn, Xatu has a good few tricks up its sleeve, including the newly introduced Dazzling Gleam which is a useful weapon against the late game dragons; while not the most durable Pokémon in existence, partly due to its stats and partly due to its typing, it can prove itself surprisingly capable against several foes.
Courtney/Matt (Mt. Pyre): Camerupt wins by 2HKOing with Rock Slide, but Xatu can 1-2HKO Sharpedo with Grass Knot or Dazzling Gleam if it manages to outspeed it, since Ice Fang is also a 2HKO.
Rival (Lilycove City): Xatu can 2HKO Swellow with Psychic, though Swellow can be hard to hit depending on how many times it uses Double Team. Magcargo is 2HKOed as well, and its Rock Slide is only a 2-3HKO against Xatu; Breloom is an easy OHKO. Wailord, instead, can be 2HKOed with Grass Knot, which deals far more than half its health in damage, downpowering Water Spout enough for Xatu not to worry about it; Grass Knot remains a 2HKO even if Wailord uses Amnesia. Xatu also 2HKOs Sceptile with Air Slash and 1-2HKOs Blaziken with Psychic; it can also 2HKO Swampert with Grass Knot if its HP is 75% or more, the necessary amount to survive a Rock Slide from it.
Courtney/Matt (Lilycove Hideout): Camerupt once again beats Xatu with Rock Slide, but Sharpedo can be 2HKOed with Grass Knot or Dazzling Gleam if Xatu is faster.
Gym #7 - Tate and Liza (Mossdeep City, Psychic-type): Grass Knot is a 2HKO against both Lunatone and Solrock; since Xatu is weak to Solrock's Rock Slide, but resists Lunatone's only offensive move, Psychic, Xatu should hit Solrock first and deal with Lunatone later. Despite Lunatone having Calm Mind, it can only 2HKO Xatu from +3 onwards, and Xatu will have already beaten Solrock at that point.
Maxie/Archie (Seafloor Cavern): Xatu should lead with one Calm Mind and then OHKO Mightyena, which does not have any STAB, with Dazzling Gleam. If Mightyena uses Scary Face in the process, Xatu will eventually have to switch out; the Speed drop does not matter against Crobat, but it does against Weezing or Muk. Xatu can OHKO all three with Psychic at +1 in Special Attack, but Weezing's Explosion chips away the majority of its health, and Muk's Gunk Shot is a 2HKO; both moves require a consistent amount of HP to be tanked, which Xatu may or may not have left. Crobat, on the other hand, can be defeated only with the +1 boost, because Acrobatics is a possible 2HKO. Mega Camerupt can be 2HKOed with Psychic if Xatu is still perfectly healthy and at +1 in Special Attack, as both conditions are required to not be 2HKOed by Rock Slide; Mega Sharpedo must be left alone, it would kill Xatu with Crunch.
Primal Groudon (Cave of Origin, Omega Ruby only): While immune to the Primal's Ground STAB, Xatu is still 1-2HKOed by Lava Plume, and must not participate in this battle.
Primal Kyogre (Cave of Origin, Alpha Sapphire only): Primal Kyogre one-shots Xatu with both Ice Beam and Origin Pulse. Probably not.
Gym #8 - Wallace (Sootopolis City, Water-type): Xatu may use Calm Mind against Luvdisc until it reaches +4, then OHKO Luvdisc with Psychic and the rest of Wallace's team with Grass Knot. It is important that Xatu be healed from confusion induced by Luvdisc's Water Pulse or Sweet Kiss in the process, as it could otherwise get hit by strong moves such as Sealeo's Aurora Beam or Milotic's Ice Beam.
Wally (Victory Road): Xatu can solo Wally by setting up against Altaria and then OHKOing every Pokémon with the appropriate moves: Altaria with Dazzling Gleam, Delcatty and Roselia with Psychic, and Mega Gallade with Air Slash. Magneton has Sturdy, and can only be 2HKOed. Although this is possible starting at +3 in Special Attack, Xatu should use Calm Mind for at least one additional turn to improve its chances of survival; Magneton's Discharge can deal almost half of its HP in damage even at +3, and so can Mega Gallade's Slash; in addition, Xatu is unlikely to fight them from full health, since it will have three or more battles behind its back at that point. Altaria allows just enough room for a +3, but Xatu must be healed during the fight if further boosts are needed.
Elite Four Sidney (Ever Grande City, Dark-type): Xatu can take a Crunch from Mightyena, use Calm Mind once, and then OHKO Sidney's team with Dazzling Gleam. Sharpedo knows Aqua Jet, but it is the only Pokémon that can hit before Xatu (barring Shiftry's weak Fake Out), and a quarter of its health is sufficient to survive the blow.
Elite Four Phoebe (Ever Grande City, Ghost-type): Xatu 2HKOs Dusclops with Shadow Ball; Dusclops' Shadow Punch is only a 3HKO, but Xatu does need to switch out if Dusclops uses Curse instead. It can switch back in against either of the Banette, if still at full health; after a Calm Mind, their Shadow Ball turns from a 2HKO into a 3HKO and Xatu can OHKO them with Shadow Ball directly. Xatu can also fight Sableye and OHKO it with Dazzling Gleam if its Calm Mind is still in effect and/or its health is still full, but not otherwise, since Sableye's Foul Play can take out up to around 90% of Xatu's HP. Lastly, a Xatu at +1 and well over half health 2HKOs Dusknoir as well, but falls to Ice Punch or Thunder Punch - both of which are 2HKOs - under different circumstances.
Elite Four Glacia (Ever Grande City, Ice-type): Xatu can only 2-3HKO the lead Glalie, whose Crunch is a 3HKO. Both of the Froslass outspeed it, the second Glalie 2HKOs with Freeze-Dry, and Walrein has high OHKO chances with Blizzard. There is no room for Xatu to use Calm Mind here; Reflect can work as a leading move, but Xatu is still outsped by Froslass and their Snow Cloak can make them dodge hits.
Elite Four Drake (Ever Grande City, Dragon-type): Xatu needs to use Calm Mind until it hits +3 against Altaria, then it can OHKO all of Drake's team with Dazzling Gleam. It is recommended that only Xatu with a nature neutral or beneficial to Speed take this route, however, as Xatu with a Speed-lowering nature are likely to be outsped by Flygon and/or Salamence, and the physical Flygon can 2-3HKO Xatu with Rock Slide, while Salamence 2HKOs with Dragon Rush.
Champion Steven (Ever Grande City, Steel-type): Although Xatu could theoretically get several Calm Minds off against Skarmory, if healed every few turns, setting up is unlikely to prove useful in the long term: Aggron's Stone Edge is a show-stopper, OHKOing Xatu from full health, and Aggron's Sturdy makes it impossible to OHKO. A possible workaround is Reflect, supported by Light Clay, alternated with Calm Mind; if Xatu manages to get to +5, it can 2HKO Skarmory and Aggron with Shadow Ball, OHKO Claydol and Mega Metagross with it, and then OHKO Cradily and Armaldo with Psychic. Xatu's Reflect needs to be still active against Aggron, and Xatu's health must be at 70% or higher to survive a Stone Edge; a critical hit can nevertheless kill Xatu. Mega Metagross' moves can deal up to about 60% when Reflect is up, which is relevant due to Mega Metagross' higher Speed; without Reflect, even Bullet Punch comes close to 2HKO range. Since no Pokémon other than Skarmory offers Xatu actual room to renew a Reflect, Xatu needs to reactivate it the very turn before defeating Skarmory in order to have hopes of it lasting the whole battle.
Post-Game: Not a place for Xatu to be; the legendaries are way too fast and powerful for it. Dazzling Gleam may, however, turn out useful against Zinnia.
Xatu starts off with a moveset that consists of Ominous Wind, Confuse Ray, Air Slash and Wish. While Air Slash is obviously very good, and Ominous Wind may be somewhat useful, Wish usually will not be, as Xatu's base HP is not that high and its capability of taking hits is far from legendary. The moves learned at earlier levels are not very interesting, either, except Tailwind for teams that need more Speed. At level 35, Xatu learns Psychic, and is set for the rest of its days as far as STAB goes. The remainder of the level-up set is not as amazing: there is Miracle Eye at 39, only really handy for Psychic monolockes and even less so with a secondary STAB; then Psycho Shift at 43, too situational and not supported by adequate bulk; Future Sight at 49, more powerful than Psychic but not enough to warrant waiting several turns for it to hit; Power Swap and Guard Swap at 53, both of which can serve their purpose against a somewhat narrow range of opponents, but not otherwise; and lastly, Me First at 57, which is actually a good move for Xatu with higher-than-average Speed, and may allow it to face some self-super effective types more easily, such as Ghost or Dragon.
More special coverage is available through TMs. Psyshock can replace Psychic to hit special walls harder; Shadow Ball offers a response for fellow Psychic- and Ghost-types, though Xatu should generally not fight Ghost-types unless there are no other options, and it can be backed up by Calm Mind. Other very good options are Grass Knot and Dazzling Gleam, the latter especially for Dark- and Dragon-types. These moves alone allow Xatu to have a fairly wide coverage, and their power can be boosted with Calm Mind. Defensive sets can run Reflect and/or Light Screen, though Light Screen is only preferable to Calm Mind in the event that Xatu is built for support; in that case, it can also run U-turn to leave the battlefield with a parting shot, potentially also dealing decent damage.
DexNav Xatu will not get many more options to work with on a special or support level, though they do get physical coverage in the form of Zen Headbutt and Drill Peck, as well as Sucker Punch, though special sets tend to work best.
Ground-types: Despite the Ice weakness, which Xatu also has, Ground-types are the only possible complement to Xatu's Electric and Rock weaknesses; fortunately, Water-types are commonly found, and can compensate for the Ice weakness, especially considering that Ice moves are not exceedingly common in Hoenn. Water/Ground-types, or other dual types that are neutral to Ice, are much better than pure Ground-types as Xatu's teammates.
Water-types: Water-types complement Ground-types in helping Xatu cover for its weaknesses; a Water-type is necessary if Xatu and a Ground-type are on the same team, unless the Ground-type in question is also part Water. For the purpose of this role, having the Thick Fat ability is a plus, as it protects the Water Pokémon even from Freeze-Dry.
Dark- or Fairy-types: For Xatu's Ghost and Dark coverage needs, Dark- and Fairy-types are best: the former can defend well against both types, but are not as good as the latter at hitting enemy Dark-types for good damage. Ghost-types should be avoided, since they are also weak to Ghost; dual Dark-types can work better on the offensive against their Dark colleagues, but must also not have shared weaknesses with Xatu.
Xatu's Reflect and Calm Mind provide good support for its otherwise average defenses. In any case, having more physically or specially bulky Pokémon on the team is advised, for matchups in which setups are not possible.
Minimum stats are calculated with 0 EVs, IVs of 0, and a hindering nature, if applicable.
Maximum stats are calculated with 252 EVs, IVs of 31, and a helpful nature, if applicable.
Natu Line Ratings
What Nature do I want? Modest is the best Xatu can get, while Timid will give better success chances to Me First users. Attack-lowering natures and/or Special Attack-boosting ones in general are very good, considering that Xatu is not made to take hits and its numerous weaknesses make it vulnerable to a number of opponents.
Which Ability do I want? Magic Bounce is best, though the others are also varying degrees of good, depending on the situation and enemy. Early Bird may be better for nuzlockers with healing limits, as Synchronize will not work in a number of cases: Poison-types inflicting poison, Fire-types inflicting burns, Electric-types inflicting paralysis, and so on.
How good is the Natu line in a Nuzlocke? Not exceptional, but good. It can outspeed several foes and has a fairly wide movepool to play with, making it surprisingly versatile. Its weaknesses and average Defenses make it somewhat risky to use in a number of situations, but it still does its job well if it stays within its comfort zone.