Here's the list of Legendary Powers, which the Mega Rangers use to summon the past Power Rangers' powers.
Legendary Powers by Team
Mighty Morphin Power Rangers
DinoTank Zord Rex Mode: The Power Rangers' Legendary Power is part of a trio of Legendary Powers granted to Zador (Megaforce Silver). The Legendary Power of the Power Rangers is granted to him by Tom Oliver (Green Ranger), where it is incorporated in one of the DinoTank Megazord's alternate modes, the Tyrannosaurus Dinozord & Dragonzord-like Dino Tank Zord Rex Mode.
Ninjor: The creator of the Power Coins, he was an ally of the Power Rangers. He sealed himself within a pot in the Temple of Power to hibernate for nineteen years before being released. After the Mega Rangers release him, he decides to observe the Mega Rangers to see if they are worthy to have the Alien Rangers' Legendary Power. The Mega Rangers then gain Ninjor's approval & gained the Alien Rangers' Legendary Power, which unknowingly was himself. Ninjor is the final free Legendary Power the Mega Rangers have obtained.
NOTE: It's unknown why he's called the Legendary Power of the Alien Rangers as he only fought alongside the Power Rangers. It's probably because in Ninja Sentai Kakuranger, his Sentai counterpart, Ninjaman, fought alongside the Kakurangers (the Alien Rangers' counterparts).
The Legendary Power of the Zeo Rangers was supposed to be granted by Kat Hillard (Zeo Ranger I Pink) as per a plan made by the Zeo Rangers, but it ended up being Tommy Oliver (Zeo Ranger V Red) when the Mega Rangers went over to face Simon.
It is used in the completion of the Super Megaforce Blaster, which is similar to the Zeo Cannon. The Legendary Power itself is to bring the powers of a team together for a devastating attack.
The Legendary Power of the Turbo Rangers: While the Legendary Megazord is able to perform an attack that resembles the finishing attack of the Turbo Megazord, TJ states that the Turbo Rangers' pose is the actual Legendary Power of the Turbo Rangers, leading Kaizo to believe that some Legendary Powers are useless.
The Turbo Rangers' Legendary Power was granted to the Mega Rangers by TJ Johnson (Red Turbo Ranger), after they manage to appeal to a crowd of children for TJ's traffic safety act.
Mega Winger's Mega Wing: The Mega Winger was the personal zord of the Silver Ranger to fight alongside the other Space Rangers; he usually let the Space Rangers use a Mega Wing glider to become the Winged Mega Voyager. Similar to this, the Legendary Power of the Space Rangers gives the DinoTank Megazord the Mega Winger's Mega Wing, the formation being called the Winged DinoTank Megazord.
The Legendary Power was granted by Andros, the former Red Space Ranger, after the Mega Rangers helped him fix the Astro Megaship, as per a deal.
The Legendary Power of the Galaxy Rangers is transferred to the Magna Defender Key by Mike Corbett after his approval & gives it to Zador after Simon tried to actually take the Legendary Power from Mike.
When the Magna Defender Key is inserted into the DinoTank Megazord, it a spinning bifurcation attack similar to the Defender Torozord's signature finisher.
Hydro Blasters: When the Mega Rangers use the Lightspeed Rescue Keys, they summon five large Hydro Blasters from the Legendary Megazord's hatches & cannon. The hoses allow the Legendary Megazord to perform the Hydro Blast attack, dousing any sort of fire with five streams of highly-pressurized water.
The Lightspeed Rangers' Legendary Power was granted to the Mega Rangers by Dana Mitchell (Pink Lightspeed Ranger).
DinoTank Zord Drill Mode: The Time Force Rangers' Legendary Power is part of a trio of Legendary Powers granted to Zador (Megaforce Silver).
The Legendary Power of the Time Force Rangers is granted to him by Eric Meyers (Quantum Ranger), where it is incorporated in one of the DinoTank Megazord's alternate modes, Drill Mode, where it is summoned from the 31st century & functions much like the Time Force Rangers' Time Flyers.
Red Lion Wildzord: The Red Lion Wildzord's totem Wildzord, the Red Lion Wildzord normally resides on the island Animarium since the defeat of the Orgs before the Mega Rangers & the Brute Space Empire arrived. It proceeds to knock them off, but its later acceptance of the Mega Rangers as the Power Rangers enabled it to be summoned to fight alongside them.
It can combine with the Legendary Megazord to form the Legendary Megazord with Wild Power or the Legendary Megazord with Samurai Power, the latter the result of the Samurai Rangers' Legendary Power. The Mega Rangers gain access to the Red Lion Wildzord after Troy, Noah, & Gia saved a crowd of citizens from one of the Brute Space Empire's monsters & a platoon of Mettoids, making them worthy in the Red Lion Wildzord's eyes to wield it's power.
The Minizord is the combination of two Power Spheres from Ninja Storm. Unlike its original form, the Minizord is green instead of navy blue, with elements of the Samurai Star Megazord. While the sun/moon is still on his body, it doesn't make up a majority of his body & it isn't on his chest. He combines with the Legendary Megazord to form the Legendary Megazord with Ninja Power.
The Legendary Power of the Ninja Rangers is granted to the Mega Rangers by the Wind Ranger trio of Shane Clarke, Tori Hanson, & Dustin Brooks (Red Wind Ranger, Blue Wind Ranger, & Yellow Wind Ranger respectively), after their team-up battle. Before that, however, the Minizord appeared to help an overpowered DinoTank Megazord pin down Vexacus so Megaforce Silver can destroy him.
DinoTank Megazord/Legendary Megazord with Dino Power: The Dino Rangers' Legendary Power is part of a trio of Legendary Powers granted to Zador (Megaforce Silver). The Legendary Power of the Dino Rangers is granted to him by Trent Fernandez-Mercer (White Dino Ranger), who also had given Zador his Megaforce Silver Ranger Key & the Silver Cell Morpher.
It is normally used for the DinoTank Megazord transformation via the White Dino Ranger Key, but Ethan James (Blue Dino Ranger) teaches them that when the entire Dino Thunder Ranger Key Set is used, it enables the formation of the Legendary Megazord with Dino Power, where the Legendary Jet Zord & Legendary Racer Zord is swapped for the DinoTank Megazord's arms.
Delta Runner 1: The Delta Runner 1 is the SPD Red Ranger's personal zord from Space Patrol Delta. It has a different design in this season than it had in Space Patrol Delta, with some elements from the Blast Runner.
It combines with the Legendary Megazord to form the Legendary Megazord with Delta Power. The Mega Rangers gain access to it after Sky Tate (SPD Shadow Ranger) taught Troy the true meaning of being a Power Ranger.
Mystic Dragon: The Mystic Dragon is the first combination zord from Mystic Force, formed from the Mystic Titan forms of the Blue, Yellow, Pink, & Green Mystic Rangers. Unlike its original form, the Mystic Dragon is red instead of a mix of five colors, as well as not formed from the four Mystic Rangers. It combines with the Legendary Megazord to form the Legendary Megazord with Mystic Power.
The Mega Rangers gain access to it after Jake used courage to save Troy's life, a key emotion that the Mystic Rangers use to summon their powers, during their chase against Nick Russell (Red Mystic Ranger).
DriveMax Megazord: The Overdrive Rangers' giant megazord, the combination of the main five DriveMax Zords, summoned by the Operation Overdrive Keys.
Animal Spirits: When the Mega Rangers use the Jungle Fury Keys, they summon the Animal Spirits (Tiger Animal Spirit, Cheetah Animal Spirit, Jaguar Animal Spirit, Wolf Animal Spirit, & Rhino Steel Zord). The Animal Spirits emerge from the limb hatches & cannon to allow the Legendary Megazord to perform a finishing attack.
The Mega Rangers gain access to the Animal Spirits after Jake & Emma were taught the meaning of hard work though martial art basics by Casey Rhodes (Jungle Fury Red Ranger).
Falcon Speeder: A hybrid between a falcon & a Formula-1 race car as well as the latest Zord Attack Vehicle created by Dr. K. It is summoned by the RPM Keys. As a Zord Attack Vehicle, Falcon Speeder's number is 13, with the 3 looking like three drag pipes.
The Ranger Operators' Greater Ranger Power was given by Summer Landsdown (Ranger Operator Series Yellow), though the Mega Rangers never discovered what it was until they encounter Scott Truman (Ranger Operator Series Red), who leads them to Falcon Speeder. Later, Falcon Speeder combined with the Legendary Megazord to form the Legendary Megazord with Octane Power.
Power Rangers (Super) Samurai
Symbol Power: The Samurai Rangers' main elemental kanji-based source of power, which they had used for a lot of purposes, including fighting Nighloks. The access to Symbol Power is summoned by the (Super) Samurai Keys & channeled through the Red Lion Wildzord, allowing the Red Lion Wildzord to combine with the Legendary Megazord to form the Legendary Megazord with Samurai Ranger. The merging of the Red Lion Wildzord in the chest of the megazord is similar both to the Wild Force Megazord, which was how it was originally used, as well as the appearance of the lion--like the Lion FoldingZord in the Samurai Rangers' Samurai Megazord.
The Symbol Power is accessed after the team's bonds impress Lauren Shiba (Red Samurai Ranger) & they gain her approval.
Power Rangers Megaforce
Zords: When the Mega Rangers use the Megaforce Keys, they summon their original main zords (Dragon Zord, Phoenix Zord, Snake Zord, Tiger Zord, & Shark Zord), Sky Brothers Zords, Land Brothers Zords, & Sea Brothers Zords to charge at the opponent in a finishing attack.
Power Rangers Super Megaforce
The Legendary Ultrazord is the combination of the Legendary Megazord, DinoTank Megazord, & Falcon Speeder when the Legendary Power of the Super Mega Rangers, the Ultra Cell, is used & inserted into Falcon Speeder. The Legendary Ultrazord can use the Ultra Drill slash attack with it's right arm & the Ultra Missiles attacks from the left-sided fingers.
Qi: Qi is the Myth Rangers' main power source. The ability to gain access to Qi is obtained during the return of Azima of where it is accessed after the Super Mega Rangers gain the Myth Rangers' approval.
The Legendary Power resurfaces later, as well as the Myth Rangers, & during the fight, the Super Mega Rangers in the Legendary Megazord accessed the power of Qi for the finishing attack, where the Pirate Megazord charges immense levels of Qi within itself, then infuses the energy into the DinoTank Megazord, then attacks (while being backed by the Legendary Megazord) drill arm-first through the target.
Lost Power Rangers
The Masked Rangers' Legendary Power was granted to them by the Red Masked Ranger during the return of his old enemy, Blackcross.
The Legendary Power of the Jacker Rangers was granted to the Super Mega Rangers by the White Joker Ranger during the return of Blackcross.
The Legendary Power of the Battle Rangers was given to the Super Mega Rangers by the Black Battle Ranger during the return of Blackcross.
The Legendary Power of the Power Rangers was granted to the Super Mega Rangers by the Blue Power Ranger during the return of Blackcross.
The Legendary Power of the Sun Rangers was taken by Simon. After the Super Mega Rangers defeated him, it was formally issued to the rangers by the Red Sun Ranger.
The Legendary Power of the Super Rangers was granted to the Super Mega Rangers by the Super Black Ranger during the return of Blackcross.
Super Dynamite: The Explosion Rangers' original group finisher. The Explosion Rangers' Legendary Power was granted to the Super Mega Rangers by the Pink Explosion Ranger during the return of Blackcross.
The Legendary Power of the Brain Storm Rangers was granted to the Super Mega Rangers by the Red Brain Storm Ranger during the return of Blackcross.
Earth Power: The mysterious yet very powerful energy utilized by the Legend Rangers during their tenure as an active Power Rangers team. The Legend Beasts Legendary Power summons the Earth Power of all the Legend Rangers & stores it within the Legendary Megazord's main cannon then fires out the cannonball-like mass of energy with immense force in the attack.
The Legendary Power of the Sonic Rangers was taken by Simon. Where & how Simon obtained the Legendary Power is unknown: due to the Sonic Rangers' biology, they can only last a limited period of time on Earth before the effects of the Anti-Sonic Phenomenon kicks in.
After the Super Mega Rangers defeated him, it was formally issued by the Green Sonic Ranger.
Light Power: Light is the main energy source manipulated & controlled by the Spirit Rangers; this is similar in concept as the Legend Rangers' Earth Power, the Myth Rangers' Qi, & the Jungle Fury Rangers' Jungle Energy. The Legendary Power of the Spirit Rangers allows for Light to surround the Legendary Megazord's right hand, which does a front flip-flying karate chop.
The Spirit Rangers' Legendary Power was taken by Simon sometime before he took the Legend Beasts Legendary Power & the failed attempt at the Zeo Legendary Power. After the Super Mega Rangers defeated him, it was formally issued by the Blue Spirit Ranger.
Super Bio Battledroid: The combination of the Bio Rangers' Battledroids, as well as the first combination of two individual megazord into a single powerful megazord, the Super Bio Battledroid returns via the Bio Academy Keys by transforming the Legendary Megazord into said Battledroid for the finisher. The Bio Rangers' Legendary Power was granted to the Super Mega Rangers by the Yellow Bio Ranger for Noah Carver gaining an understanding about the importance of life.
The Legendary Power of the Racer Rangers was granted to the Super Mega Rangers by the Red Racer Ranger during the return of Blackcross.
The Legendary Power of the Geo Rangers was taken by Simon. After the Super Mega Rangers defeat him, it was formally issued by the Yellow Geo Ranger.