Might i suggest using Asuka for the "Dish Best Served Cold" achievement?
Her reversal doesn't need any special timing since you can literally hold b+1+3/2+4 (A+X/Y+B) and wait for the training dummy to attack with a mid/high (set CPU actions in defensive training).
And for the "Below the Belt" achievement, this can be obtained in practice mode also using Defensive Training Mode really easily against Alisa's Triple-Click move.
Set the CPU to perform it and then just hold df. You will eat the first 2 hits but automatically parry the 3rd low kick at all times. So it will require no skill or timing on the players part.
PLEASE NOTE THAT IF I GET A RANDOM FR WITHOUT A MESSAGE, I'll DECLINE IT.