If you've only been playing League of Legends for the last year or so, you've likely never been introduced to Lulu, a champion who was, at one point, thought to be one of the few champions that was eternal, or whose value transcended metagames. While Lulu was originally designed to play the support role, it quickly became apparent that her potential was best unlocked as a mid laner thanks to her excellent AP scaling and her brutally strong laning phase. Lulu reigned as one of the top mid laners in the game for years, until a horrific nerf to her primary damage skill, Glitterlane, left her completely helpless when facing down huge stacks of minions.
Lulu's role is a simple one, but she's one of the best examples in League of a champion being powerful specifically because they excel at doing one specific thing better than anyone that shares their role. In Lulu's case, that thing is completely hosing melee champions. Quite literally every single skill that Lulu has on her kit is, at best, obnoxious for melee champions to deal with, and some of them are downright lethal for the relatively fragile assassins that have often proven popular in League. One of the main reasons why Lulu was so everpresent for years on end was her ability to completely shut down Zed in teamfights -- turns out giving an assassin's target an extra 1.5k hp makes it hard for them to get the kill they're looking for. That is, if the assassin in questions even gets a chance to attack their target in the first place. Whimsy can easily turn a terrifyingly dangerous Zed into nothing more than a cupcake, and one easily slain at that.
As it turns out, Lulu is quite capable of doing all of these things even without the gold income that the mid lane offers her. Support Lulu is not something that's been seen on a regular basis in League since the months following her release, but she's now proving to be one of the premier supports in the game. The biggest reasons for this are two-fold, and both apply to solo queue just as much as they do the competitive scene.
The first reason has to do with her laning phase. Lulu matches up quite well with almost every other support in the game, as she's quite potent against some of the strongest laners in the game, while also having the teamfight impact that a more sustain-oriented support would likely lack. Much of that is due to her passive, Pix, which helps her directly counter two of the biggest supports in the game right now, Malzahar and Zyra. The extra hits that Pix bestows upon whoever it's blessing helps Lulu or her ally to instantly clear both Zyra's plants and Malzahar's voidlings with only one or two auto-attacks, which largely neuters both of those champions in lane. Pix is not less helpful against other types of champions, however, as melee supports will quickly find themselves weathering a storm of pixie bolts, and Lulu is one of the best champions in the game at countering melee suuports for that reason. Lulu's laning isn't all-powerful, however. Dedicated laning picks like Nami and Soraka are still extremely difficult, and Lulu does have trouble being effective if she and her lane partner fall behind early on in the game, as her kit quickly weakens if Lulu ever finds herself under leveled.
Strong laning isn't Lulu's only asset, however, as she also excels at shutting down whole clases of champions in the all important teamfightiing stage of the game. While she isn't the hardest assassin counter in the game -- Kayle and her instant cast, huge range ultimate likely takes that honor -- she's pretty close. As previously mentioned, Whimsy is one of the most effective anti-assassin spells in the game, as it not only mitigates the damage an assassin might deal, it often prevents them from dealing any damage in the first place. Nothing is more soul-crushing as a Zed player than getting an amazing flank onto the enemy ADC, only to get turned into a cupcake and slaguhtered the moment you try to do anything with it. Considering lethality champions remain popular in nearly every role, this is no small asset. Whether it be a Rengar, a Kha'zix, a Lee Sin, a Talon, a Zed, or an Ahri, you can bet that at some point in any given game your ADC is more likely than not going to get jumped on by some kind of assassin, and there's little better responses possible from a support that to polymorph said assassin while they're trying to make a dramatic entrance.
Do take note, though, that Lulu isn't a champion that you want to simply take into every game, regardless of composition. Without the right champions on her team, Lulu can struggle mightily to have any impact on teamfights against other defensively minded teams. While there definitely is combo potential with Wild Growth's knock-up, it's heavily reliant on having something like a Zac or Malphite on your team that can get into the enemy team's backline easily. If the enemy is running a team that's built around defending, say, a Viktor and a Kog'maw, then Lulu's lack of offensive pressure may well spell doom for your team, especially compared to picks like Alistar or Braum, both of whom have the tools to help put the pressure on any kind of hyper carry the enemy team might have.
When used properly, however, Lulu is simply one of the best supports in the metgame right now. Her ease of use is extraoridinary, as the most difficult decision you'll pretty mcuh ever make as Lulu is simply figuring out what targets on your team you need to hit with Wild Growth, as well as which target on the enemy team needs to eat a Whimsy every time a fight breaks out. If you master those decisions and learn to navigate Lulu's laning phase, you'll have no shortage of spare LP after the wins you pick up.