Saban’s Mighty Morphin Power Rangers: Mega Battle's story is a different origin than the TV series. In this game, the five teenagers, Jason, Zack, Billy, Trini and Kimberly, discover an odd crystal and find themselves under attack. They are then transported to a strange base where Alpha-5 and Zordon not only explain that the Earth is under attack, but also grant the teenagers the ability to morph into fighters.
The game is spread across several locations, each with three levels, and in pretty much all cases, the first level is short, the second is the longest with a bulk of the location's enemies concentrated in one place, and the final one puts the Rangers up against a major villain that results in some time fighting in the Zords. There are a couple of exceptions to this pattern, but in most cases, this is what you can expect. While there is a heavy wash-rinse-repeat pattern to the game's structure, it kind of fits given the same feel from the TV series.
As you progress in the story, you will also meet Tommy and get a similar introduction to the Green Ranger that mimics the original series, eventually leading to unlocking his character. So what do the different characters get you? While they each have their iconic weapons that have different effects and strengths, the real differences come in the stats that the Rangers possess. Each one is balanced a little differently so that one will have better martial arts skills, while another's health or strength is higher. All that being said, the characters all ended up feeling very similar, so who you play as ends up coming down to personal preference over anything else.
As you progress in the game, the Rangers gain experience as enemy drops in the form of energy balls. When you level up, you can spend points to unlock various abilities in the skill tree that each Ranger has. These different skills are everything from stat boosts to better weapon usage, co-op attacks, or new fighting moves. By the time the character is at the max level, everything can be unlocked and the Ranger is a fighting force to be reckoned with.
While Mega Battle can be played, and beaten, in a single-player mode, up to four players can join forces to work through the levels, and Mega Battle really pushes for you to play with friends. For one, if a Ranger goes down, then another one can revive him/her so the game doesn't have to end there. Other multiplayer benefits include co-op attacks that can be unlocked and, after you've finished the story, a Dojo Mode that lets players fight each other.
Beating the Story Mode also unlocks a Survival Mode called Rita's Tower and a Boss Rush Mode where you can go through each of the main villains either as Rangers or by fighting in the Zords.
Speaking of Zords, as you would expect, most boss battles end with Rita or Lord Zed growing the monster and forcing the Rangers to call upon their huge mechanical robots to continue the fight. These fights are in two stages. The first stage is in Tank Mode where the players fire weapons at targets on the monster and then shoot down blasts that it sends at the screen. Once this stage is done, the Megazord goes into Battle Mode and the game takes on a fighter look, but instead of standard fighter controls, the players work together to perform quick time sequences in order to judge how well the Megazord pulled off the attack it was attempting. If you do well, you can overpower the enemy's attack and deal a lot of damage, but if you only do okay, then you just block that attack. A failed attempt yields damage to the Megazord and occasionally the two fighters will be equally matched and the players have to rapidly press a button in order to overpower the enemy's attack.
While this was an interesting way to integrate the Zords into the game, I felt like this was typically the weakest part of the experience. The Tank Mode segments felt very rote and required little thinking, while the frustration inherent in the quick time sequences just added to the overall blah-ness of what should be epic battles.
As a side note, there is a DLC that adds a few more characters to your list of Rangers. Not only does Tommy's White Ranger version become available, but you also get the Season 2 Rangers, Rocky, Aisha, Adam and Kat, as well as an alternate version of Billy. At the time of this writing, this DLC is available for purchase, but it doesn't actually become available for use until sometime in March. As a result, it's unclear if these are new characters you can choose from or if they are just different skins for the human form of the Rangers.