Android18a
Member

Hi Folks, thought I'd compile a list of the most frequently asked questions about this game, since we keep seeing the same questions asked repeatedly. I'm trawling the OT for repeated questions and I'll compile them all here for ease of use.
If you have any questions about the game, check here first, since it's probably been asked!

My 3D isn't working!
This game only uses 3D in certain events, and during battles. On the regular overworld the 3D is turned off.
How big is the download version?
About 14,000 blocks.
Can we still Critical Capture?
Yes, Critical Capture still occurs. This is when you throw a Pokeball, and it shakes whilst in the air. This is a very reliable capture, that seems to occur more as you catch more Pokemon.
Can I use TMs more than once?
Yup, they are still infinite use as in Gen V.
How does EXP Share work in this game?
Pokemon who fight get 100% exp (unsplit), Pokemon in party get 50% exp (unsplit). It's been called overpowered, but it helps a lot for levelling out your party evenly. Stops your grass/bird Pokemon falling behind in an ice cave, for example.
Can you explain Super Training, Pokemon-Amie?
Pokemon-Amie Guide
Please PM me with a Super Training Guide if you find one.
Any seasons or Day/Night cycle?
Day/Night cycle remains, but seasons are gone. Unknown how this affects Deerling and Sawsbuck.
Where can I get Heart Scales easily?
Try this guide on Reddit!
Is there any Streetpass on this game?
Yes, it's hidden in the Holo Caster. You've probably not looked there, so go check it out.
Can I find out what moves do in battle?
Yes. Hold the L button as you select a move to bring up its information.

How many new Pokemon are in this game?
The Pokedex seems to top off at 718 at this point, ending in Xerneas, Yveltal and Zygarde.
Can I use the GTS to find Pokemon that aren't in my Pokedex?
Yes! At the bottom of the alphabetical list, tap "What Pokemon" and you can enter the name of the Pokemon you're after. So want a Ditto early on? Just ask for it!
How can I Mega Evolve?
This happens as part of the story. Expect it at roughly 10 hours in, depending on your playstyle. You'll need to obtain the Mega stones for most Pokemon individually, although your Kanto Starter, Torchic Event and
Lucario
How often can I Mega Evolve?
Once per battle. But it costs nothing so you can do it in any battle.
What are the version exclusives?
X <--> Y
Clauncher <--> Skrelp
Swirlix <--> Spritzee
Staryu <--> Shellder
Pinsir <--> Heracross
Sawk <--> Throh
Houndour <--> Electrike
Poochyena <--> Purrloin
Aron <--> Larvitar
Xerneas <--> Yveltal
Also Charizard X and Y, and Mewtwo X and Y.
What's a Shiny Pokemon?
A shiny Pokemon is an extremely rare color variation of a Pokemon that has a sparkle effect when it enters battle. The sparkle part is important; a few Pokemon like Hippopatas, Basculin, Shellos, and Vivilion have common color variations based on gender or region, and these do not have the sparkle effect. The most famous example of a shiny is the red Gyarados from Gold and Silver, which is one of the few scripted shiny encounters. I'd recommend keeping a healthy supply of Pokeballs at all times on the off-chance that you see one; they're REALLY rare.
Is this a Shiny Pokemon!?
Toxi said:A Shiny Pokemon will have a red star on its status summary screen. In battle, they will sparkle as they appear. If in doubt, catch it to be sure. If it's not a shiny, you've only lost a Pokeball or two. I'd recommend using False Swipe to lower the Pokemon's HP to make sure it doesn't die (beware recoil from attacks and weather effects, though...)
The Daycare man won't call me over if he has an egg!
When the Daycare has an egg for you, the man will face the path of route 7. If there is no egg, he'll be facing towards the daycare pen.
What Pokeball should I use?
Under normal conditions? Ultra Ball
At the start of a battle? Quick Ball (first turn only, VERY reliable)
At night? Dusk Ball
At sea? Dive/Net Ball
Do Shiny Pokemon have shiny box icons?
No.
What are the benefits of using Pokemon-Amie?
EXP Boosts, increased changes of critical hits, Pokemon shrugging off status ailments... it's worth doing! Oh, and your Pokemon looks at you during battle!
Do the Poke-Ami boosts work in Wifi Battles?
As far as I can tell, no. It would probably make games quite unfair.
What is Pokerus, and how do I get it? How do I keep it?
Pokerus is an extremely rare 'disease' your Pokemon can catch through contact with infected Pokemon in the wild. It has no negative effects, it merely increases the amount of bonus you get through EV training. Pokemon with Pokerus usually heal overnight, meaning the benefits continue but they lose the ability to spread the disease. To prevent this, keep a 'mon with live Pokerus in your boxes. Or a few of them! If you're lucky enough to get Pokerus, infect some random stuff and send it out into wonder trades!
Breeding takes ages...
Keep a Pokemon with Flame Body in your party to greatly increase the speed of egg hatching.
What fossil should I pick?
Jaw Fossil for Tyrunt
Sail Fossil for Amaura
How do I get good Wonder Trades?
It's random, so just keep trying. If you trade a Bidoof, you're part of the problem.
Where's my Torchic?
Use Mystery Gift from the main menu, then get it via Wifi connection. The Torchic is only available for a limited time.
What is the little silver disc beside some of my Pokemon names?
This shows your Pokemon knows a Field Move. For example: Surf, Flash, Fly, Rock Smash, Strength. Moves which can be used outside of battle, such as HMs.
What Pokemon do I ride in the overworld?
As far as I've found: Skiddo, Gogoat, Rhyhorn, Mamoswine, Lapras (with surf). Maybe more?
How do I get Sylveon?
Video guide! Thanks to @lex!

Is there a map of Lumiose City?
Yes
How do I enter the boutique in Lumiose City?
Getting yourself known in the city helps. Trim your Furfrou, fight in cafes, visit the museum etc.. also this:
Getting into the boutique requires you to be wearing a stylish enough outfit. Buying a bunch of stuff from Anistar and wearing that seems to be the best way to get in, I'm not sure of the specifics for male trainers but for females you seem to just need to trigger the pink flower flourish effect when the game shows you the outfit you chose (default is music notes).
How many female hairstyles are there?
During the main quest, 8 hairstyles. And here's the colours.
As for the haircuts you can unlock pigtails and ponytail as options for female trainers. Unlocking conditions seem to be fully based on getting a lot of haircuts, although I did so while wearing a "stylish" outfit as well. You'll know when you unlock the haircuts because the lady will have different dialogue when you walk in the door to the salon.
Can I take off my hat?
Nope, you keep your berries under there.
When do I find the second gym, did I miss something?
Stay the course, you'll get there. There's a very long space between the first and second gyms, but the rest are much closer together.
How do I get more outfits?
Most boutiques change their wares daily. You can see if a town has a boutique on the town map by tapping on the town. It appears that the female trainers have a wider range of outfits to collect.
How to find more O-Powers?
Look for Mr Bonding in hotels and Pokemon centers. Using a power a lot will unlock a higher powered and more expensive version.
Why should I wear shorts?
They're comfy and easy to wear.
Should I tip? What does it do?
Can't find a conclusive answer just yet. Current speculation is that it affects shiny rates. Unconfirmed.
DON'T save in Lumiose City?
Horrible Bug - A few Pokemon X & Y players are reporting a problem saving their games in Lumiose City, one of the game's hubs. Saving in and around the streets outside the city have caused the game to lock up, forcing players to manually shut down the 3DS by holding down the power button. Once rebooted, the game loads the save and then freezes yet again in an infinite loop. You can see a video of this glitch above. This save glitch has been found in both physical and digital copies of the game.
Okay, that's all I can see in the time I have available. I hope this helps at least a few of you!!
Credit for some questions goes to GAF and Reddit