Ad hoc trophy
An ad hoc trophy is a trophy for a Playstation Vita game that can only be earned in ad hoc mode (i.e., local multiplayer mode requiring at least two Vitas). Due to the relative unpopularity of the Vita, ad hoc trophies are often extremely difficult to earn, as actually tracking down another player that not only has a Vita near you, but also owns a copy of the same game, is oftentimes impossible.
Games with trophies requiring ad hoc play
Here is a complete list of all games with ad hoc trophies. As there have been no new additions to this list in a couple of years, it seems unlikely that any more games will be released with ad hoc trophies in the future.
| Dead or Alive 5: Plus
The Keep Your Enemies Close trophy requires you to play a single match in ad hoc mode. The other versions of Dead or Alive 5 do not have any ad hoc trophies.
|Disney Epic Mickey 2: The Power of Two|
| Dynasty Warriors: Next
The Equipment Collector trophy requires at least 2 (preferably 3) Vitas to play together in ad hoc mode to earn some of the pieces of equipment, some of which have fairly challenging requirements.
| Looney Tunes Galactic Sports
The Making Friends requires you to play a single game in ad hoc mode. This trophy came into existence in May 2015, making it the last ad hoc trophy ever created.
| Michael Jackson The Experience HD
The A Glove for Any Occasion! , Figure Collector , and Still Not Enough! trophies all require 2-player ad hoc mode. The PS3 version of the game could originally be platinumed via online multiplayer, but its Facebook integration no longer works, so its platinum is unobtainable.
|ModNation Racers: Road Trip|
| No Heroes Allowed: No Puzzles Either!
The Villainy Loves Company trophy requires you to play one game in ad hoc mode.
|Street Fighter X Tekken (Vita)|
| Table Ice Hockey
The Defeat the Human trophy requires you to win a single game in ad hoc mode.
| Table Top Tanks
The War Room Owner trophy requires you to win 5 games in ad hoc mode.
The 通信バトルで勝利した trophy requires you to play one game in ad hoc mode.
Games with trophies *almost* requiring ad hoc play
There are some other trophies that don't technically require ad hoc play, but they are designed in such a way that obtaining them any other way would be extremely difficult, expensive, or otherwise unreasonable. These trophies are summarized here.
| One Piece: Unlimited World Red
If playing on the Vita, the Friends on My Side trophy requires you to complete a single quest in ad hoc mode. However, the game's trophy list is shared with its PS3 version, so the trophy can also be earned by playing the game on PS3 with two controllers.
AD-Hoc Required for Plat at the PlaystationTrophies.org forums