What it does
During harsh sunlight, Leaf Guard prevents the holder from being inflicted with Burn, Paralysis, Sleep, Poison, or Freeze. The immunity covers both direct moves (Will-O-Wisp, Spore, Toxic) and passive contact triggers (Flame Body, Static, Poison Touch).
The immunity is active only during harsh sunlight. Change the weather, end the sun, and Leaf Guard provides nothing — the holder can be statused normally outside sun.
Leaf Guard prevents new status conditions; it does not cure existing ones. If the holder is already burned before sun comes up, the burn stays.
Who runs it
Tsareena (1%) has pure Grass typing and a reasonable Attack stat (108), but its 1% Champions usage reflects limited competitive footprint. Leaf Guard only matters if the team is running sun.
Leafeon (2%) is a physical Grass-type with 110 Attack and 95 Speed. In a sun team, Leaf Guard keeps it status-clean while it hits with Leaf Blade and similar moves. The 2% indicates this is a niche build rather than a consistent presence.
How to use it
Leaf Guard is a sun team ability. Without a sun source on the team, it provides zero benefit. With reliable sun, it functions as a passive status immunity that frees up the item slot you'd otherwise use on Lum Berry or Safety Goggles for status prevention.
In doubles, item slots are competitive. A Pokémon that doesn't need to carry its own status insurance because Leaf Guard handles it in sun can use that slot for Life Orb, Choice Band, or another offensive boost. That's the concrete upside.
The clearest use case: you know the opponent runs a sleep lead (Spore) or a Will-O-Wisp support. Under sun, none of that touches your Leaf Guard holder.
Tips & strategy
Leaf Guard is prevention only. Status inflicted before sun goes up stays on the holder. If your Pokémon gets status-burn|burned on Turn 1 and you bring sun on Turn 2, the burn is already there and Leaf Guard can't remove it.
Weather control is the core dependency. A rain team opponent flips your weather off; sunlight ends; Leaf Guard goes dormant. Plan for how to maintain sun if Leaf Guard's immunity is part of your strategy.
Flower Veil is often confused with Leaf Guard — Flower Veil prevents both stat stage drops and status conditions on ally Grass-type Pokémon. The distinction from Leaf Guard is that Flower Veil covers allies and is not weather-conditional, while Leaf Guard only protects the holder itself and only in harsh sunlight.