Power Plus

Power Plus, also known as Str Up, Power Source, and ATK Boost, is a recurring item in the series. It permanently raises a character's Strength by 1, and is usually a very rare item in the games it appears in.

Final Fantasy
Appears only in the Dawn of Souls and 20th Anniversary versions. It is usually found in the optional dungeons such as Whisperwind Cove and Lifespring Grotto, and can only be won from one enemy in the entire game.

Final Fantasy VII
Power Sources can be found throughout the game, and can also be morphed from Unknown 1, Heavy Tank, and Screamer.

Final Fantasy VIII
Str Up can be stolen only from Raijin at Balamb. It can only be gotten through Refining 1 Monk's Code for 1 Str Up or 10 Hyper Wrist for 1 Str Up.

Final Fantasy Crystal Chronicles: Ring of Fates
ATK Boost can be bought for 500 and increases Attack by 1.