Ok i'm pretty new player, but i just had a long session with a lambda player. This may be cause i wasn't playing a top lambda, but from what i saw he can't really punish you from jumping unless he catches you in the first few frames of the jump. So block his first few D's and then keeping jumping and blocking while mixing up super jumps and dump jumps while blocking. He will be forced to shoot anti air swords which opens up a quick dash in 5b. Basically i would do things like jump forward block jump forward block jump forward block then dash in 5b and vice versa but walk forward block instead. Super jump over his ground sword wall thing (idk what its called but it removes a primer) and mixup blocking and airdashing since he will often follow up with anti air swords because you can't IAD over it