The Blue Bloon, as a cheap bloon, is best used with cards that synergizes with swarms of cheap bloons, such as Bloon Embiggen or Bolstered Bloon. However, most competitive aggro strategies don't use Blues, due to their 2 delay and Gold cost, though okay for budget decks that can't afford better aggro cards.
Blues can be combined with Reds on Turn 1 if the starting hand has one Blue card and two Reds, but do note that the opponent can still afford two Spike Storm!, Firestorm, or at least two cards worth of Dart Monkey Twins by the time that the Red+Blue Turn 1 spam becomes a threat.
Delay increased ― 1 → 2
Health increased ― 50 → 60
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Screenshot from before the health nerf in v3.2
