Battle Moveset

A Good Moveset for Glalie would have to be this:

Attacks:

Ice Beam
Explosion
Light Screen/Crunch
Spikes

Items Attached:

LeftOvers OR
Salac Berry

Preferred Nature:

Gentle or Sassy

Strategy Using Glalie

Glalie is a bit like a crappy Celebi with a useless type (at least from a defensive point of view). It gets an interesting move pool although it can't really excel in any area. Getting Glalie into play is pretty difficult but once it's in play set up a Light Screen and rejoice if you're facing a special sweeper after you've set up screen. After that, Spike as much as you can (you won't be seeing many layers of Spikes from this guy) and prior to fainting, Explode on something. Ice Beam is just there for a supportive move in the process so that you aren't left totally helpless. Salac Berry will probably telegraph that you're about to boom but it will help you get the Explosion in prior to fainting, however Leftovers is the safe choice.

It's not advise to try your luck with Glalie in OU but if you intend to you can pretty much set up on Blissey before booming on her (for a very nice OHKO) and you can also easily set up against Skarmory. To Glalie's credit, no one in their right mind would send in their Claydol or Donphan to Spin it's Spikes an Starmie users would have to think twice due to a potential Crunch (hence it's inclusion as an option). It also doesn't get messed up by Magneton like Skarmory and Forretress. Unfortunately, it's merits at being able to counter Spiker-counters doesn't make up for the difficulty you'll experience trying to get up a full layer of Spikes.

EV Corner:

For Glalie's being used in a UU environment:

EVs: 204 HP / 90 SAtk / 216 SDef
Sassy Nature (+SDef, -Spd) or Gentle Nature (+SDef, -Def)

Glalie can achieve a 275 Special Defense, which is pretty decent by UU standards. Throw in Light Screen and you should be able to take a few special hits. The rest is maximum Leftover recovery and whatever was thrown into Special Attack for stronger Ice Beams. If you intend to use a Salac you might want to throw on some more Speed so that you can out-speed the majority of sweepers prior to Booming.

For Glalie's being used in the OU environment:

EVs: 252 Atk / 20 Def / 58 Spd / 180 SDef
Gentle Nature (+SDef, -Def)

You want Max Attack (neutral nature) for a guarantied OHKO when Exploding on Blissey and enough speed to outrun the Pokémon that linger around that area. You'll want that little bit of Defence so that you won't be OHKOed by DD Salamence (in other words, you can switch in when it DDs, take its HP Flying then OHKO it with Ice Beam and still be left with enough HP to Explode later on). Whatever EVs that are leftover you'll want in your Special Defence, for what it's worth (it's worth more than putting it into your Defence, since Water Pokémon will be switching in to block your Ice Beams and they'll be Surfing your Special Defence), or though putting them into HP would be acceptable, as would putting a little extra into Special Attack to KO certain Pokémon you've experienced some problems with.

Other Optional Sets:

Glalie @ Choice Band
EVs: 82 HP / 252 Atk / 176 Spd
Adamant Nature (+Atk, -SAtk) or Lonely Nature (+Atk, -Def)
- Shadow Ball
- Earthquake
- Explosion
- Ice Beam/Hidden Power [Rock/Bug]

Glalie is a pretty crappy Choice Bander but it gets enough physical moves to try. Most of the time you'll find yourself using Explosion but Earthquake and Shadow Ball are both good physical moves to use when you can (and the fact that they cover what Explosion can't hit for neutral damage is very nice). Ice Beam gets STAB and therefore remain useful even when you're hitting hard (well, hard-ish) with your physical moves, while Hidden Power has the versatility factor.

Glalie @ Leftovers or Salac/Petaya Berry
EVs: 82 HP / 176 Spd / 252 SAtk
Mild Nature (+SAtk, -Def)
- Ice Beam
- Hidden Power [Electric or Fire]/Substitute
- Crunch
- Explosion

Glalie also has a decent enough move pool to try and special sweep, although it gets let down by its terrible stats once more. Hidden Power [Electric] could be used for a psuedo-Bolt-beam with Ice Beam while Hidden Power [Fire] is super effective against Steel types (who resist the other 3 moves). Substitute could be used to activate a berry and is a useful enough filler for those unable to obtain a good Hidden Power. Explosion will take out any Special walls that try to stand in your way.

Strategy Against Glalie

It's an Ice type, which pretty much sums up how screwed it is when it comes to weakness count. Rock, Steel, Fire and Fight make the prestigious list of types that screw Glalie up. Steel types will especially mess up non-EQ (or HP Fire) Glalies since both Ice Beam and Explosion are resisted. If you see Glalie begin to spike, don't be hasty to send in your Rapid Spinner (unless your Spinner isn't one of the standard 3) since Glalie will destroy Claydol and Donphan while Starmie is at risk to a potential Crunch. It's best to wait it out, making it run with something like Metagross and then spinning when it's outta the way. Predicting when it's gonna explode (and all good Glalie's carry Explosion) will mess up all its efforts. Pretty much any sweeper not weak to Ice attacks can destroy Glalie or force it to Explode, so sending in a good solid sweeper will do the trick.

Contest Moveset

A good Contest Moveset for Glalie would have to be this for the Beauty Contest best with Modest, Mild, Rash or Quiet Nature:

Attacks:

Hail
Ice beam
Explosion
Blizzard

Items Attached:

Blue Scarf

Strategy Using Glalie

If you do the attacks in this following order you should have very few problems; 1st - Hail, 2nd - Ice beam/Blizzard, 3rd - Hail, 4th - Ice beam/Blizzard, 5th - Explosion

Locations in Games

Ruby/Sapphire/Emerald Evolve Snorunt Colosseum Trade from RSE Fire Red/Leaf Green Trade from RSE

Animé Appearences

Glalie has had a few Animé Appearences. First it evolved from Ash's Snorunt while Ash was training it. After that it became one on Ash's Strongest Pokémon in the Hoenn League taking out Pokémon such as Charizard & Sceptile. Ash then left it at Oak's Laboratory as he went to the Battle Frontier Episode 400: Decisive Battle! Grand Fesitval (3)! Episode 402: EverGrande City Arrival! Meowth In Boots?! Episode 403: Start the Preliminaries! Masamune Enters! Episode 405: To The Tournement Finals! Every Day A Heated Battle! Episode 406: And...Continue the Battle that Cannot Be Lost! Episode 407: Rival Confrontation! VS Masamune! Episode 408: The Last Fierce Fighting! The Road To The Championship! Episode 410: Oak's Laboratory! All Member's Gather!