Moves
Spore is used to cripple foes and to more safely guarantee recovery with Strength Sap. Moonblast is Morelull's main Fairy-type STAB move, and is very useful for hitting common threats such as Vullaby, Mienfoo, and Scraggy while also having a fairly good chance to lower the foe's Special Attack stat, which can become quite annoying to deal with in conjunction with Strength Sap. Giga Drain is Morelull's Grass-type STAB move and is another good form of recovery, able to score a KO while recovering HP. Strength Sap is very unique and quite good in Little Cup because, unlike other forms of recovery in the tier, Morelull gains more than 50% of its HP back by using this move against most physical attackers, and it weakens their offensive potential by lowering their Attack. The move is less effective against special attackers, however. It is also important to note that Strength Sap deals no damage. All in all, it is a fairly good move, and it is one of Morelull's main niches over Foongus.
Set Details
Morelull's EV spread is used to maximize its Defense and Special Defense when used with Eviolite, and the HP and Special Attack EVs help Morelull's pivoting potential. A Bold nature also helps to maximize its Defense. Eviolite boosts Morelull's Defense and Special Defense to help it take hits better. Effect Spore is the only viable ability on Morelull and it certainly has its perks, as it can passively apply status without Morelull needing to use up a moveslot, but it can sometimes incorrectly status the foe with what you don't want it to, such as poisoning a sweeper instead of paralyzing it or putting it to sleep.
Usage Tips
Due to its bulk, Morelull can freely switch into any resisted attack and many neutral attacks. Try to avoid staying in on Poison-types such as Croagunk, Mareanie, and Stunky. Using Strength Sap to heal up when you predict a physical attacker switching in can both heal Morelull and lower the Attack of said foe. However, even when pivoting, never be careless with letting Morelull lose excessive amounts of health, as its recovery is not passive like Foongus's, and it doesn't work very well against special attackers.
Team Options
Other pivots, particularly offensive ones such as Mienfoo, Chinchou, and Magnemite, are good partners for Morelull's playstyle and can help get it in without taking too much damage. Salandit, although particularly niche, has good type synergy with Morelull, resisting Poison-, Fire-, and Steel-type moves, and it can help break opposing walls for Morelull. Mareanie also has good type synergy with Morelull and can help with resisting the ever-present Water-types of Little Cup. Pawniard also boasts good type synergy and a similar wallbreaking nature with Knock Off. A special wall such as Munchlax can help cover some attackers that Morelull can't beat such as Abra. Rapid Spin and Defog users can help keep Morelull from taking damage every time it pivots in. Diglett can trap Poison- and Steel-types for Morelull that would otherwise threaten it.