While I do think Lurantis is out-classed generally speaking, it's not so terrible it can't work at all, I think. In lower tiers, I'm sure it will do well enough. After all, barring Contrary Leaf Storm, Serperior was a fairly hard pokemon to do much with, and now it's been solidly OU. I don't see the same fate for Lurantis given its speed, but it's enough of something that it can work. It just wishes it had better coverage options or other moves to take advantage of the contrary ability. Anyway, a few sets I had in mind.
(First off, pretty much all these sets are assuming you're using sun at least, and trick room with some of them.)
Lurantis @ Life Orb
Ability: Contrary
EVs: 4 HP / 252 SpA / 252 Spe
Timid Nature
- Weather Ball
- Hidden Power Ice/Ground
- Giga Drain
- Leaf Storm
This one is fairly simple, maximizing speed and your damage output as much as possible. Max Speed Lurantis is still outspeed by plenty, but you will find yourself outspeeding a lot of uninvested tanks and the like. Generally, you will just want to hit Leaf Storm and pray, but I think this provides the best potential coverage of all your options (limited though they are) Giga Drain is redundant but will give you some healing and will hit hard after a leaf storm or two. Whichever HP you want is up to you. HP Ice will leave you walled by fire types but you probably wouldn't want to stay in on them anyway. HP Ground leaves you only walled by Fire/Flying and Dragon/Flying types, and nets more SE hits overall. Under the Sun, weather ball becomes a base 100 fire attack that's boosted by said sun making for effective coverage, overall.
Lurantis @ Leftovers
Ability: Leaf Guard
EVs: 252 HP / 252 Attack / 4 Def
Adamant Nature
- Solar Blade
- Brick Break/Poison Jab
- Synthesis
- Aromatherapy/Defog
Probably not the best set in the world, but if you were wanting to do a more support/utility set while still having damage potential, then look no further. We're using leaf guard cause if you're under the sun, then no status will bug you, which goes well with the bulkier nature of this set. Solar Blade is still a 125 BP STAB attack coming with max attack investment. Brick Break or Poison Jab is up to you. Poison Jab gets you more neutral hits overall, but Brick Break lets you do something against steel types. Synthesis keeps you healthy. Since leaf guard is the ability of choice on this set, status isn't as bad to us, but aromatherapy is an option just for healing the team. Defog works as well to remove hazards.
Lurantis @ Leftovers/Life Orb
Ability: Leaf Guard
EVs: 252 HP / 252 Attack / 4 SpA/ 0 speed IVS
Brave Nature
- Growth
- Leaf Storm
- Solar Blade
- Leech Life/physical or special coverage move of your choice
This set requires the most support to be sure, but has the most pure damage potential as a mixed wallbreaker, I feel, which serperior lacks. You need a trick room setter and a drought pokemon to make the most of this set, which is why the brave nature works and 0 Speed IVs just to make it as slow as possible. You'll want max attack investment since you're already going to be boosting SP.Attack with growth and leaf storm. The idea is you come in, and growth, you boost both attacking stats by two, then either leaf storm (also boosting your Sp. Att by 2 again) or solar blade depending on what you see with leech life as recovery (which will do pretty solid damage on most things at +2) or whatever coverage you feel is best. Weather Ball can work to deal with steel types and other grass types, or Brick Break to deal with steel types, or the hidden power of your choice. Leftovers you should use with Leech Life just to maximize tankiness and survivablity, but if you want to run another coverage move, then Life Orb will maximize damage output. Again, this set is limited by the support it needs to work, but when you have that support, I feel this is the best potential set. Just as an example to see what we can do once set up.
+2 252+ Atk Life Orb Lurantis Solar Blade vs. 0 HP / 4 Def Garchomp: 520-614 (145.6 - 171.9%) -- guaranteed OHKO
252 Atk Life Orb Garchomp Fire Fang vs. 252 HP / 0 Def Lurantis: 304-359 (88.3 - 104.3%) -- 25% chance to OHKO
So we have a decent chance of surviving the hit from the life orb garchomp and then OHKO'ing it. (again, presuming trick room here)
+2 4 SpA Life Orb Lurantis Weather Ball (100 BP Fire) vs. 252 HP / 168 SpD Ferrothorn: 712-842 (202.2 - 239.2%) -- guaranteed OHKO
And the ferrothorn can't do much to us in return, besides switch out, and give us a free turn of setup.
+4 4 SpA Life Orb Lurantis Leaf Storm vs. 252 HP / 144+ SpD Sableye-Mega: 324-382 (106.5 - 125.6%) -- guaranteed OHKO
This is where the mixed capabilities come into play as burn doesn't bother us too much as long as we keep leaf storming.
4 SpA Life Orb Lurantis Weather Ball (100 BP Fire) vs. 252 HP / 4 SpD Aegislash-Blade: 403-476 (124.3 - 146.9%) -- guaranteed OHKO
Even a non boosted weather ball takes care of certain builds of Aegislash.
And these are just common OU threats. I fully realize that in most occasions, they could just outspeed and kill us, but I just wanted to show the damage potential on this set. Presumably, Lurantis is going to be NU or RU at best, so I predict it can do even better against that calibur of competition.
And finally...
Lurantis @ Lum Berry/Leftovers/Life Orb/Sitrus Berry
Ability: Leaf Guard
EVs: 252 HP / 252 Attack / 4 Defense
Adamant
- Swords Dance
- Solar Blade/Leaf Blade
- Leech Life
- Brick Break/Poison Jab
This is your traditional bulky set up sweeper kind of set, and I do think it's a little outclassed by like Leafeon or Shiftry in terms of physical grass types that can swords dance, but I felt remiss to not mention such a set. The item is up to you, and dictates your EV spread. I went with Lum Berry first of all, just because I know I hate more than anything getting burned while I'm trying to set up. Then we have leftovers which just gives you useful sustain when combined with leech life. Life Orb can work just to make the most of your damage. With that set, you'll want to max out speed and maybe go for a jolly nature just to outspeed as much as humanly possible. Sitrus Berry is another option, which works best with the bulkier spread but anyway. It'll give you that extra burst of healing that can help more in a pinch than leftovers. Say you take a hit that does about half your health, then sitrus berry activates and you're at solid health and you got your swords dance.
The idea is pretty simple really. Just swords dance, and hope for the best. This is another set that I presume you'll be using sun for, but this is one where it isn't required, and can be run on a more regular team. Either way, if you are using sun, then go Solar Blade. IF not, just use leaf blade which is probably more consistent anyway. Then you got leech life for recovery, and your choice of break break/poison jab. Either one leaves you walled by something. Contrary is the ability of choice, even if likely it won't do much for you. In the right situations, it will give you boosts from say defog or intimidate or sticky webs or what have you.
Overall, I'd say Lurantis will likely struggle in the OU tier and probably UU, but contrary leaf storm is just a great combo. Being able to do damage and set up in one move is something very few pokemon can do. With its ability to defog and heal as well giving it added utility, it has the potential to do well in RU and below, I'd say, (with that growth mixed set not being something to sleep on, I bet you) With some extra moves to take advantage of contrary and just for more coverage, it could be really good in later games.