I main carl, and I can give you guys some tips
I find that most people in general spend too much time on trying to poke out nirvana. As in they they hit her and start poking. It's a good idea, depending on where the carl is. If I'm close enough, I'll hit you with C, or I can do C 4D 236 B, then proceed to ground loop and mixup, or throw loop.
Most tagers seem to think that once they are close enough to carl, and nirvana is kinda far away, that sledging towards carl and trying to rush him down is the right thing. It can work, yes, but all carl has to do is jump and poke poke poke. Most carls use pokes alot, as it gets us out of being rushed down. Carl's air pokes are actually very good. If the carl knows what he is doing, then he can turn a simple air poke can into a throw loop.
Try not to burst too early. Most tagers, infact most players in general, seem to burst right when I hit confirm them into a ground loop, or they see that I'm juggling them in the air and about to start his throw loop. Not all carls are good at the throw loop, and most carls do the "bootleg" version of the throw loop. Bootleg meaning it works, but it's not really the "correct" loop and it can be escaped, so to speak. Tech out of the first throw and see how he responds. If he is able to juggle you back into it, then by all means tech out and burst, as most likely he knows how to do it correctly. If you tech the instant you are grabbed and nirvana doesn't clap, then that means that he is doing the clap too late, and he doesn't know how to loop very well. If you tech, nirvana claps, but he doesn't dash and either 2C or B 9 B C 8D and continue loop, then that means he doesn't yet know how to loop very well also.
if the carl can loop correctly, you've already burst, and nirvana has enough meter, then just get ready for the next round. DON'T TECH OUT OF EVERY THROW. Most people seem to think that teching out of every throw is a good idea. All that does is reset the combo and now 2C 8D take a lot more damage, and the carl doesn't have to throw loop you anymore, all he has to do is just clap loop you to death (2C 8D). Look at nirvana and see if she has enough meter. If she doesn't and you think you might survive, then let him loop you until the last throw. Tech out of the last throw as nirvana would be broken and can't clap. Now proceed to rushdown, but be careful, good carls know how to fight without nirvana and they can play runaway until she comes back.
Carl players try and either get you between carl and nirvana, or back you up into a wall. It's already obvious not to get between carl and nirvana, but most people don't seem to know that it's also not a good thing to let carl back you up into the wall. Carl has corner loops, which lead into throw loop. Try not to back up to much into the wall, and considering that nirvana's anti airs can hit tager even when he is grounded and tager can't air dash, backing up to the wall is a death sentence for tager.
Patience is key. Using carl requires patience, and fighting carl requires patience. Many people I fight try and rush me down, only to get throw looped. Carls have to know how to handle beinged rushed down, and have to know how to turn that rush down, from their opponent, into an advantage. So be careful, don't think because you have carl in the corner with nirvana on the other side of the stage that it's time to just rush down. Carl's can combo you into loop, even when nirvana is on the other side.
And last but not least, pay attention to where nirvana and carl are. Their positioning will determine what you can and cannot do. Footsies, backdashing, sledging, patience and well timed aggression is key in this match. Infact footsies and patience are key when facing a good carl in general. Cause any mistake can lead to loop, and unless you're one of the 4 characters, then 2 mistakes and it's game over.
I hope that helps.