Smogon official tier: LC
Base Stats: 62 HP, 50 Attack, 58 Defense, 73 Sp. Attack, 54 Sp. Defense, 72 Speed
Abilities: Rivalry, Unnerve, Moxie (HA)
“Usable” moves (according to Pokémon Showdown): Crunch, Dark Pulse, Endeavor, Façade, Fire Blast, Fire Fang, Flame Charge, Flamethrower, Frustration, Hidden Power (Electric, Fighting, Fire, Grass, Ice), Hyper Voice, Overheat, Payback, Protect, Rain Dance, Rest, Return, Roar, Sleep Talk, Solar Beam, Substitute, Sunny Day, Taunt, Toxic, Wild Charge, Will-o-wisp, Work Up, Yawn
This analysis will answer a potential question concerning Poké Monday: What if the generated Pokémon is not fully evolved? That doesn’t matter. Most first-stage Pokémon (excluded: Gligar, Scyther, Sneasel, Swirlix, Tangela, Yanma, Meditite, Murkrow) belong in an official tier called Little Cup where everything is Level 5 and EV investment becomes “confusing.” For more information, please consult the following URL: https://www.smogon.com/forums/threads/a-little-help-a-guide-to-the-intricacies-of-lc.3497933/
As for second-stage Pokémon, there is no official tier (well, there is Middle Cup, but it’s not nearly as official as LC), so I will analyze their usability in whatever tier they are in (usually NU, but there are exceptions: Combusken, Doublade, Fletchinder, Gligar, and Golbat are RU; Porygon2 is UU; Chansey is OU (even though Blissey is UU)). But, those analyses are for a later time.
Looking at Litleo’s stats, it looks to be all-around with specially offensive bias. Unfortunately, it is cursed with a bad set of abilities (Rivalry is too situational to be of competitive use, Moxie doesn’t bode well with its subpar Attack stat, and even Unnerve is bad thanks to Berry Juice being legalized) and a lacking movepool (albeit normal for a Fire-type). In the end, though, its main use lies in being a special attacker. It can also use Taunt to deal with hazard leads, although keep in mind that its max Speed is only 4th-highest in the tier (tied with base 63-72). Here is one set I used:
Litleo @ Life Orb
EVs: 252 SpA / 76 SpD / 180 Spe
– Fire Blast
– Hyper Voice
– Dark Pulse
This set is a straightforward stallbreaker with dual STAB, Dark Pulse (mostly for Frillish, although I haven’t encountered many of those while testing), and Taunt. Sadly, this set falls short in that it can’t handily deal with bulky things and it’s too slow to be any sort of offensive presence. Another set I thought of is Scarf+Moxie, but that’s even less capable of dealing with bulky things.
Litleo @ Choice Scarf
EVs: 196 Atk / 132 SpD / 180 Spe
– Fire Fang
– Wild Charge
Really, you can’t bring this thing in unless the opponent is below half and either is not resistant to Return or is weak to any of its other moves. Physical Litleo just that weak without any boosts under its belt; therefore, it is not a very effective sweeper.
However, I managed to come up with another physical set that utilizes Litleo’s average bulk, interesting typing, and access to Flame Charge and Moxie:
Litleo @ Eviolite
EVs: 180 HP / 196 Atk / 84 SpD / 20 Spe
– Flame Charge
– Wild Charge
Flame Charge can boost its 4th-rate Speed (which is even lower when Adamant) to new levels and carve a potential opportunity to sweep with Moxie. Return is for sheer power, Wild Charge takes care of Water-types (namely Frillish) and hits Flying-types hard, and Will-o-wisp is mainly just there in case of Geodude and Onix (both of which wall this set). Long story short, it can sweep through unprepared teams.
Other options: Bulldoze (not listed in usable moves) and Crunch are additional options for coverage on physical sets. Work Up could be used on a mixed set, although it would need the added bulk of Eviolite and/or speed of Flame Charge. Hidden Power is a coverage option on special sets, but its nerf to 60 is detrimental and coverage is less important in LC. Overheat is another considerable option on special sets, but the Special Attack drop forces you to either switch, resort to physical moves (if applicable), or deal with being weaker than a Nosepass. Yawn can be used on non-Scarf sets to force switches and/or induce sleep.
All in all, Litleo is more of an offensive presence than anything. It’s not the most offensive thing in the tier, but it should definitely not be overlooked. Here is the most successful team I created while testing, which features Flame Charge+Moxie Litleo: http://pastebin.com/qT2K64n2
Again, comments/questions are always welcome (but please, no trolling).