There are multiple ways to unlock the characters of Super Smash Bros. Ultimate by playing the different game modes that it offers. Through the game’s World of Light, Versus, and Classic Modes you can unlock Ike in Smash Bros. Ultimate.
Ike can be unlocked quickly by completing just a few rounds of Classic Mode, but he is unlocked in Mario’s character unlock route in Classic Mode so you will need to have beaten this mode with other specific characters to unlock them. To unlock Ike in Classic Mode you will need to have beaten it with Mario, Sonic, Bayonetta, or Little Mac. The next time you play with Mario, Sonic, Bayonetta, or Little Mac and complete the Classic Mode you will be able to challenge Ike for the character unlock.
The fastest way to unlock Ike in Super Smash Bros Ultimate
Ike is actually not unlocked in the World of Light mode until halfway through it. In Classic Mode, you can unlock Ike after beating it with four characters. This can take about 30 minutes or so. There are other methods which involve starting and restarting the game, but it’s probably a little bit more time consuming if you’re just looking to unlock this specific character.
So quickest way to unlock Ike in Super Smash Bros. Ultimate is definitely to go about it by beating Classic Mode with Mario, Sonic, Bayonetta, or Little Mac as described above. Otherwise he’ll take a little while to unlock.
Simply head into Classic Mode, play on any difficulty, and beat the six stages, bonus level, and boss battle. Once you’ve completed Classic Mode with Mario, Sonic, Bayonetta, or Little Mac you will then see the New Challenger Screen which starts the fight with Ike.
You will need to beat Ike in a one on one match to add him to your roster. Once you do you will have permanently unlocked Ike in Super Smash Bros. Ultimate. However, if you lose to Ike in the one versus one match he will not be unlockable via this method for a little while. You can still unlock other characters in Mario’s Classic Mode Route though. If you lose to Ike, the character that you can unlock leapfrogs Ike in the case of Mario, Sonic, or Bayonetta it would be Luigi.
After a bit of time this rematch will be available in the Games & More section of the main menu. If you want to go back and unlock Ike but you lost the first time, head to the Challenger’s Approach and then fight them again to unlock.
Mario Route Classic Mode
All of the characters in Mario’s Route can be unlocked with the ones before it in Classic Mode. Meaning Mario will unlock Sonic, Mario and Sonic can unlock Bayonetta. Mario, Sonic, or Bayonetta can unlock Ike, and so on. If you fail to beat one of the challengers to unlock them, it will then skip to the next challenger. The one that you lost to will reappear later.
Mario > Sonic > Bayonetta > Little Mac > Ike > Luigi > Roy > Dr. Mario > Olimar.