I gotta say, only a highly skilled white knuckle player can be as good as all that to make blaster an infinite win machine. There are a few gamers, whom I've run into that I imagine use a game controller to play FFT and spend hours of their lives every night practicing. Yes, THOSE blasters will be unbeatable.
But every player has a pattern of movement that becomes almost robotic, so sit in the base for a moment and watch where the blaster is constantly going. I'll bet you he'll be zooming between bomb loads to reload, and skimming inbetween the hanger most often, if not sitting on top of the hanger and just aimlessly shooting at scared noobs in a noob team's base.
My suggestion to you is to get a high dpi mouse, and turn the in-game sensitivity way down. You'll be a much better sniper/player for having done so, once you get used to it.
First line of attack is gunner. The trick is, constant jump/shift and always staying in motion. As a gunner you've got a bit more maneuverability on your side even if you aren't as fast. So instead of waiting for the blaster to come to you, hunt the thing, and always be on it's back. As long as you have shatter bombs, you'll be ok. I've even killed Marshals as a guest gunner, so I know it's not that hard.
Second is blazer. But this comes down to having a good team. Wait in the corner and watch for the right moment. Blazer can see all the players anywhere they are, so hunting the blaster shouldn't be that hard. A highly skilled blazer can make the game heck for a blaster if the team you're on is good and serving as decoys. At this point, again be at the blasters back and above him and roast it.
As mentioned, Tank can get the job done. Turn up your mouse's dpi and lower the in-game sensitivity to almost nothing and take the lock off of his gun. This makes the rapid fire tank much more deadly as long as you can master being accurate without the lock on. (This is impossible if you use a trackpad like I did for the first 3 years of playing this game)
You can actually almost-fly with tank in TDM arena, staying in the air almost all the time by looking straight up when pressing E and then using the jetpack wisely. This isn't very useful of course, but just something to play around with if you're in an empty arena.
To some it may not seem so, but the shocker can prove deadly to a blaster. Using the bubble gun to knock his stats down, and then freezing him midair, plus shock gun, can kill it, so long as you always stay in motion, thus disorienting the blaster.
Basically, what I am saying is the Blaster provides a challenge for you to become more highly skilled. I personally wouldn't vote to change anything about it, even if I didn't own it myself, because it can make a dull game fun. I have beaten a good blaster in at least 4 of the other classes besides blaster. And nowadays, blaster isn't even my main, as shocker and gunner have my vote as the most useful classes. Just stay in motion, and don't look back to see if he's on your tail unless you're ready to face him. Blasters don't expect to be hunted, and it changes their play style into something out of their comfort zone when they are. Hunt kill, repeat. Chances are, your main problem is not being on a good team. A good team can make all the difference in winning/losing.
As a side note, once you do get blaster, you'll probably like it the way it is.