Can be anything from swellers, trich enhancers or anything else besides basic grow and bloom mixes. I'm a huge fan of silica and kelp. Not loyal to any brand.
Kelp all day. Seems a big stress reliever so as a novice it's been important. Tried three and GO's bioweed is my favorite. Even in the garden, foliar with it after transplant and see immediate results.
While I don't transplant in the traditional sense (just upgrade rockwool cube size) I totally agree. I use after topping and defoliating and see very little to no shock time. I also use it for the bloom transition. I love kelp.