Paulus Hector Mair - "Arte Athletica" 1540 - Ringen (Wrestling)
These images are taken out of context of a much larger collection of images, showing extensive techniques for Ringen in two major works on Renaissance Martial Arts exploring all possible forms of arms.
The reason for collecting these images is that the topic of grabbing clothes in medieval and Renaissance wrestling was discussed on various forums. These are the images I found in Mair. I may gather more images of grabbing clothes eventually.
Wrestling in armour on the other hand, often seems to involve grabbing the visor of the opponent's helmet, as can be seen here: Jacob Johann von Wallhausen images and is also described here: The Deeds of Jacques de Lalaing - Feats of Arms of a 15th Century Knight.
Grabbing a belt.
Grabbing the family jewels.