If there's a single word that describes Wigglytuff, it's "outclassed". While her movepool is titanic and chock full of marvelous moves, her relatively poor stats and Normal typing hinder her. Her huge HP stat is dwarfed by her horrendous base defenses, and her mediocre offensive stats hinder her from doing much damage outside of Seismic Toss. Being a Normal-type, Wigglytuff also has to compete with numerous other Pokemon that boast massive movepools, and most of the time, they'll have better stats all around, as well as a couple of other nifty moves that Wigglytuff misses out on. However, one shouldn't discount Wigglytuff immediately; with her particularly large support movepool, she can be quite an effective supporter, despite how outclassed she is in that role. In the end, know that Wigglytuff is not a truly bad Pokemon; she's just so horribly outclassed that it's hard to justify using her over any of the other viable Normal-types in UU, and even NU.
When it comes to defensive Normal-types, Wigglytuff definitely isn't a popular choice in UU, as she is horribly outclassed by Clefable, Chansey, and Lickilicky. However, with useful support moves in Wish, Heal Bell, and Thunder Wave, as well as passable defenses, Wigglytuff can still be fairly effective in that role.
Wish is a fantastic move to heal weakened teammates with, and provides valuable team support. Protect can scout for troublesome moves, and alongside Wish, forms a means of reliable recovery that allows Wigglytuff to stick around for quite some time. Seismic Toss is Wigglytuff's best form of offense against most foes, and, while it doesn't do amazing damage, it is the best option Wigglytuff has in that regard (while Wigglytuff's STAB move, Hyper Voice, might seem better, it really only does more damage against frail Pokemon like Sceptile). The last slot depends on what kind of support you need for your team. Heal Bell is a useful option if your team is vulnerable to status, while Toxic and Thunder Wave cripple walls and sweepers, respectively. However, if you lack a Pokemon with Stealth Rock, Wigglytuff can use it in the last slot instead.Team Options & Additional Comments >>>
While Wigglytuff would seem to be another generic dual screen user, her large support movepool enables her to stand out amongst the sea of possible options. Boasting access to extremely helpful moves in Wish, Heal Bell, and Stealth Rock, and plenty of bulk to use both screens and her support options, Wigglytuff can prove to be an effective user indeed.
Reflect and Light Screen help bolster Wigglytuff's mediocre defenses. Stealth Rock support is very important, as some sweepers, such as Belly Drum Linoone, just barely miss out on some necessary KOs against some Pokemon at full health; thus, Stealth Rock is essential to allow these Pokemon to nab these KOs. The last slot depends on what you feel your sweeper will appreciate the most. Heal Bell's ability to cure status can help your sweeper later in the match if your sweeper had been burned or paralyzed earlier. However, Wish can essentially give sweepers a second chance to sweep under screens, and can also help get a frailer Pokemon into the match. Wish also gives Wigglytuff some more longevity to use Light Screen and Reflect with. If you feel that your desired sweeper doesn't need either support option, Seismic Toss is an option to do decent damage and prevent Wigglytuff from being rendered completely useless by Taunt.Team Options & Additional Comments >>>
With a titanic movepool, Wigglytuff has plenty of other options that she can use with some success. As far as alternative support moves go, Wigglytuff has access to Sing, Knock Off, Sweet Kiss, and even Charm. With her nice bulk, she can use the effects of all of these moves to an extent. However, for most of these moves, they're either too unreliable, or have effects that aren't as good as the other support options that Wigglytuff has access to. Wigglytuff also makes a respectable user of Gravity, with plenty of moves that benefit from it such as Sing, Fire Blast, Thunder, and Blizzard. However, with mediocre offenses, she fails to be outstanding at abusing it offensively, while her defenses also aren't quite good enough to continually switch into attacks to set it up. Perish Song would be a fantastic move to use on Wigglytuff; however, the fact that it's incompatible with Wish makes it a less-than-stellar option. Fake Tears and Tickle are options to potentially cause switches and soften up opposing Pokemon, but are poor options in general. With Wigglytuff's huge HP stat and low defensive stats, she makes a respectable user of Counter, though unfortunately, her lack of a one-turn recovery move, and low Speed make it difficult for her to pull it off continually and makes it really only worth it for the surprise value.
Physically, Wigglytuff has plenty of options to abuse. Return, Focus Punch, Ice Punch, ThunderPunch, and Fire Punch are just a small portion of the physical attacks that Wigglytuff has access to. Because of this, Wigglytuff can make a decent abuser of a Choice Band or physical Life Orb set, though her mediocre Attack stat prevents this from being a great option. Specially, Wigglytuff has even more options, boasting strong attacks such as Hyper Voice, Ice Beam, ThunderBolt, Fire Blast, and Grass Knot to give a basic idea of how diverse her movepool is on the special side. Like on the physical side, Wigglytuff can use a Choice Specs or a Life Orb set with decent success. Unlike the physical side however, Wigglytuff has access to a boosting move in Charge Beam, which, while not particularly amazing, can help bolster her barely acceptable Special Attack. You could also try to mix some of her physical and special options to turn Wigglytuff into a mixed attacker; however, despite the astounding coverage that Wigglytuff would have with this kind of set, it's still easy to wall due to Wigglytuff's poor offenses.
Checks and Counters
Wigglytuff's defenses, while decent, are not really top-notch, and strong attackers such as Aggron, Hitmonlee, and Rhyperior should be able to break through them with ease. In particular, Fighting-types work well, as they immediately threaten Wigglytuff with their strong, super effective STAB attacks. However, if Wigglytuff is carrying a status move such as Toxic or Thunder Wave, you will want to use Pokemon that won't have issues with these lest you have a crippled Pokemon on your hands. If Wigglytuff is using Toxic, Venusaur makes a great counter. Swords Dance variants can set up on her easily, while support sets can abuse her huge HP stat with Leech Seed. If Thunder Wave is used, Rhyperior works well, having the ability to set up on her with either Swords Dance or Rock Polish, and threatening her from the get-go with his monstrous Attack stat. Substitute users such as Mismagius and Rotom can block her attempts to status them and can proceed to set up. Taunt will also stop Wigglytuff in her tracks, as most of the time, her best form of offense will be Seismic Toss.