Moves
Brave Bird and Double-Edge are strong STAB moves that are boosted by Reckless. U-turn allows Starly to escape unfavorable matchups and can also be used to scout switch-ins and generate momentum; it is also the only reason to use Starly over Doduo, which has better all-around stats and access to Knock Off. The last move should be one that, while not great to be locked into, can be helpful in certain situations. Hidden Power Grass hits Tirtouga and most other Rock-types for lots of damage; it is used because Starly's other options bar Steel Wing are not very effective against Rock-types, and Tirtouga takes neutral damage from Steel Wing. Steel Wing is also generally less effective than Hidden Power Grass because Rock-types are usually physically bulky; however, Steel Wing does still hit Archen.
Set Details
Reckless is the only ability of any use, boosting Brave Bird and Double-Edge to frightening levels of power. Choice Scarf lets Starly move first most of the time, allowing it to punch holes in the opposing team or quickly U-turn out. A Speed-boosting nature is used to maximize the effects of Choice Scarf. Use a Naive nature if using Hidden Power Grass and a Jolly nature if not. Attack-boosting natures can be used for more power, but Starly will be outsped by Jolly Choice Scarf Cranidos and Bunnelby, as well as Modest Clamperl and Jolly Tirtouga after Shell Smash, all of which can easily KO it. The EVs maximize Speed and Attack while slightly increasing HP and Special Attack to accommodate the use of recoil moves and Hidden Power Grass, respectively. If using a physical coverage move and a Jolly nature, move the 36 Special Attack EVs to Defense so that Starly takes less damage from priority moves.
Usage Tips
Starly can be brought in at any time in the game, provided it is safe to do so, but try to bring it in late-game as a suicidal cleaner when all of its checks are gone. Because it's so frail, bring it in through slow pivoting moves, such as Volt Switch from Chinchou or U-turn from Mienfoo, or into a predicted Ground- or Ghost-type move so that it doesn't take damage. Don't switch Starly into Stealth Rock too many times, as it will quickly be worn down. Starly is also not a good wallbreaker, so don't play it as one.
Team Options
Stealth Rock removers such as Drilbur, Archen, and Staryu are a must, as they prevent a quarter of Starly's health from being stripped off every time it enters the field. Ground-types such as Drilbur and Diglett can get rid of the Steel- and Rock-type Pokemon that resist Starly's STAB moves. Drilbur can also Rapid Spin away Stealth Rock, while Diglett can trap grounded Pokemon that trouble Starly. Starly can be used in a VoltTurn core with pivots such as Chinchou, Larvesta, Magnemite, and Mienfoo, or in a bird spam core with other Flying-types, such as Fletchling, Doduo, and Archen. Finally, entry hazards from setters such as Dwebble and Drilbur can help Starly clean up late-game.