What it does
Hospitality does one thing in doubles: when the carrier enters, the partner currently on the field recovers 25% of its own max HP immediately.
No conditions, no turn delay. The heal resolves on entry, before any moves in that turn are used. If the partner is at full HP, the excess doesn't carry over. If there's no partner on the field, nothing happens.
That 25% matters more than it sounds. A partner sitting at 35% HP is in KO range for a lot of spread moves and priority. A partner at 60% HP might not be. That's the math Hospitality shifts every time it triggers.
Because the heal fires on entry, it reactivates whenever Sinistcha switches back in. Each re-entry is another free 25%.
Who runs it
Sinistcha is the carrier at nearly 99% usage. It's built around doubles support: 120 Sp. Def, low Speed of 31 (great for Trick Room), and a moveset that includes Trick Room, Follow Me, and draining moves. The entry heal comes first, then it does its support work.
The contrast with Incineroar is useful to keep in mind. Incineroar enters and lowers the opponent's Attack with Intimidate. Sinistcha enters and heals your own partner. Put them both on the same team and the entry effects cover both directions — defensive and offensive.
How to use it
Straightforward lead application: if your main attacker is going to take significant damage on turn 1, lead Sinistcha next to it. The heal lands before any moves resolve, so your attacker starts the turn a quarter of its HP more intact than it would have been.
Revival use: if Sinistcha was benched and you bring it back in mid-game, the heal triggers again. The action cost of switching is real, but in a situation where your partner just took heavy damage, a free 25% can be worth a turn — especially when it pushes your partner out of OHKO range.
Follow Me pairs naturally here: Sinistcha draws attacks to itself while the partner acts freely with full HP, having just been healed.
Tips & strategy
The timing of the entry heal being before moves are used means the opponent may have already committed their targets. If they're planning to finish off your damaged partner, they might not account for the 25% that just came in. That's a real source of miscalculation for opponents.
In teams that cycle switches with Parting Shot or U-turn, Hospitality can trigger multiple times across a game. The cumulative healing adds up.