Here you will find a list of the various Summon Materia you can pick up while playing Final Fantasy VII (MP: shows how much MP is used every time you call that specific summon)

Powers: Elemental Wind; sometimes causes Stop
MP: 14
Location: Can be found at the Chocobo Ranch from a chocobo.

Powers: Elemental Ice
MP: 32
Location: Gained from a small girl in Junon.

Powers: Elemental Fire
MP: 34
Location: Received after killing the first Jenova.

Powers: Elemental Lightning
MP: 40
Location: May be found in the chocobo jockey room at the Gold Saucer.

Powers: Elemental Earth
MP: 46
Location: Discovered inside the destroyed reactor at Gongaga.

Powers: Gunge Lance, Steel Bladed Sword; Sometimes causes KO
MP: 80
Location: Found inside the safe in the Mansion in Nibelheim.

Powers: Elemental all
MP: 110
Location: Discovered within the Sleeping Forest.

Powers: Non elemental damage
MP: 100
Location: Gained in the Temple of the Ancients

Powers: Elemental Holy
MP: 120
Location: Found in Gaea’s Cliff

Neo Bahamut:
Powers: A more powerful version of Bahamut
MP: 140
Location: Found in the Whirlwind Maze in the Crater.

Powers: Elemental Water
MP: 78
Location: Gained after killing Godo in Wutai.

Powers: Elemental Fire; sometimes revives KO’d party members
MP: 180
Location: Found at Fort Condor.

Powers: Inflicts negative status effects on enemies
MP: 150
Location: Gained from the crashed Gelnika.

Bahamut ZERO:
Powers: A yet more powerful version of Bahamut and Neo Bahamut
MP: 180
Location: Received at the Cosmo Canyon (Huge Materia)*

Powers: Elemental Wind
MP: 160
Location: Found in the Ancient Forest.

Knights of the Round:
Powers: The power of 13 knights, deals great damage
MP: 250
Location: Knight’s Island Materia Cave (Uncharted Island in the North East)**

* Requires Bahamut and Neo Bahamut

**Requires Gold Chocobo