When the Slush Fighters first encounter Blue Uno in the beginning of their adventure back home, he challenges them, although he gets easily defeated due to how weak he is. As soon as the Slush Fighters reach the top of the tower, they discover Uno had recovered and was determined to beat them this time, although he is re-defeated afterward, along with Wicker Blue and Overly Zealous Blue.
However, in the conclusion of their adventures, the Slush Fighters find out that Blue Uno, along with his pet skunk had beaten them to Slusher and had grown more powerful than ever. With his health bar barely absorbing any damage, a block level of 5 and a dodge ability of 4, Blue Uno unleashes his strength upon the Slushers. However, despite his attempts to eliminate the Slush Defenders, Blue Uno is once again foiled for the 3rd time. His current status is unknown.
As a tutorial enemy, Blue Uno is the easiest enemy of all in the game, right before Blue Two, as it only takes 4 hits for him to be defeated. He is not able to send his own tiles against the player nor is he able to lock the player's tiles. Adding to this, he does not have block ability and even a dodge ability.
However, as the optional boss in Solarise, his fighting style changes to that of a regular Blue enemy. However, it only takes about 3 Special Moves to take him out (as shown in the tutorial), still making him an easy enemy to defeat.
In his Ultimate Form, however, he becomes a more formidable opponent. He is now able to send his own tiles against the player which lasts for 10 - 15 seconds, has a dodge ability (which activates after 4 turns) and a block ability (which blocks damages below 5). It is recommended that "spammable" Slush Fighters such as Sthang and Stedro are to be used, especially Sthang due to his burn capability in his Special Move. Blue Uno attacks after every 3 seconds, adding to this difficulty of the fight due to his tiles taking too long to be removed automatically. Sticorey is a good fighter to be used if the player has him in their team. Marcstick should also be enough to deal with Blue Uno, as his chain attacks deal incredible amounts of damage if he is used continuously, but this is quite difficult to do but is still possible. If the player is lucky enough to activate Marcstick's "Wild Strike" Special Move without encountering a "Failed Strike", it should take 3-4 Wild Strike's to finish off Blue Uno.
As Blue Uno:
- "You ain't gettin' pass me!"
- "Ow! My health!"
As An Angry Blue you beat up a couple of seconds ago:
- "I will NOT be beaten again!"
As Blue Uno in his Ultimate Form:
- "I will have my revenge!"
- "I have attained my ultimate form!"
- "I have reached my FINAL form!"
- He might have been Big Blue's right hand man, considering how strong he is compared to the other Blues (the exception being his weak form in the tutorial).
- Blue Uno is very revenge-focused, as shown with his acts against the Slush Fighters.
- He may have undergone large amounts of training for a few days, weeks or even months before fighting the fighters again.
- As the final boss, his eyes have changed and so has his design to a considerably menacing state from his frail and innocent-like appearance as a tutorial enemy and Boss.
- According to the game's coding, Blue Uno's health points are:
- 30 in his first appearance as a tutorial enemy.
- 100 in his second appearance as a Boss.
- 1000 in his third and final appearance as Ultimate Uno.
- In his Ultimate Form, Blue Uno appears to have small black marks on him.
- Ultimate Uno's quote: "I have attained my ultimate form!" may be a reference to the popular internet meme featuring something usually grossly mutated paired with the words "This isn't even my final form!"
- When fighting Blue Uno in the tutorial, a seemingly harmless glitch can be performed. If the player activates a special attack as Sthomas, Blue Uno's damage quote plays before the attack animation is even finished.
- Blue Uno can sometimes glitch out where, if his health has been diminished to zero, he will still continue battling and he will not be defeated, thus making the boss battle with him completely unwinnable. The only way to undo this is to retry the entire Slusher level.
- The word 'uno' in Blue Uno's name is Spanish for the word "one".