Generally, cloth training pants need to be easily pulled up and down, for quick trips to the potty. (Toddlers can give VERY short notice sometimes.)
For early stage of training, pants with more absorbency helps to hold at least 1 accident well. Good to have: waterproof outer layer. These are also suitable for continued training when outdoors.
For later stage of training, can use pants with only slightly thicker centre, non waterproof is good to speed up the learning.
For any training pants, ensure the inside is NON stay-dry, so that child feels wetness immediately after pee-ing.