A full Tristana skin gallery, plus the practical point: some skins change the silhouette enough to matter in a fight.
Before the cosmetics: Tristana is a marksman at 550 attack range whose job is to deal damage every second of a fight from behind people who can absorb one.

Tristana has 19 skins, excluding chromas. The art below is the in-client splash.
Skins change no numbers. They are not therefore free of consequence — a skin that alters the silhouette or recolours an ability changes how quickly an opponent reads what you just cast.
That cuts both ways, and it is the honest reason some players keep the base skin on champions they take seriously.
Increases Tristana's Attack Range as she levels.
Tristana fires her weapon rapidly, increasing her Attack Speed for a short time.
Tristana fires at the ground to propel her to a distant location, dealing damage and slowing surrounding units for a brief period where she lands.
When Tristana kills a unit, her cannonballs burst into shrapnel, dealing damage to surrounding enemies. Can be activated to place a bomb on a target enemy that explodes after a short duration dealing damage to surrounding units.
Tristana loads a massive cannonball into her weapon and fires it at an enemy unit. This deals Magic Damage and knocks the target back. If the target is carrying the Explosive Charge bomb, the bomb detonation radius is doubled.
While many other yordles channel their energy into discovery, invention, or just plain mischief-making, Tristana was always inspired by the adventures of great warriors. She had heard much about Runeterra, its factions, and its wars, and believed her kind could become worthy of legend too. Setting foot in the world for the first time, she took up her trusty cannon Boomer, and now leaps into battle with steadfast courage and optimism.
Skins are tied to the account, not to you. Anything bought on a smurf stays on the smurf — worth knowing before spending real money on one.
Full Tristana page — abilities, stats and every skin →