Can someone please explain if the number of special attack blue lines (how quickly u can release a special attack) stay the same when you evolve a Pokemon? I'm hoping I'm correct in assuming the single longest blue bar gives the most power attack... Thank you!
The blue bar isn't something that's related to the Pokemon. Instead, the blue bar (called as the energy bar) is the one that depends on the move you use.
Powerful moves, that hits very hard generally have a single solid bar, which means, it requires more energy and time to fill the single solid bar, but in return, it hits harder. On the other hand, the small bars does significantly less damage but fills up faster and can be used more number of times in a particular time period.
To answer your question - NO (in most cases). The number of bar lines doesn't stay the same as the moves changes completely after you evolve a Pokemon. If there's a move that's common between the non-evolved and the evolved Pokemon and if you've got the same move, then Yes, the bars will be the same. In short, bars are move dependent, so if the move changes, the number of bar changes according to the move.
The blue bar is based on the move the Pokemon has. While a pokemon's type and species determines its possible moves, they're more or less chosen randomly. An evolved Pokemon might have the same moves, or different ones.