The answer is to be patient and dash up, block, or dash again.
Sometimes when people see/hear three venoms go up they are waiting for a charge. At that time, I dash up about 3-4 times right into their face without stopping.
You can charge some people and they may try to dodge it or they'll simply block. If they try to dodge it without the potential to air dash, you might get them. If they simply block, you get a good chunk of block damage.
For characters that are capable of dashing in mid-air, it's not really advisable. Just dash up and see what they will do. With the venom debuff reduction set back down a few seconds, you probably have enough capacity to block a few times before reset.