The Gnome Trainer is an NPC who is located at the Gnome Agility Course. The trainer's job is to shout words of encouragement to get the player to complete the agility course.
You can kill any of the three pickpocketable gnome trainers by failing the pickpocketing.
3 of the gnomes on the eastern side of the court at ground level may be pickpocketed for 198.25 XP and varying loot at level 75 thieving. Failing to pickpocket them will initiate combat but they do not grant combat XP, and cannot be attacked unless you fail thieving. They have 11 hitpoints. After defeating them, they take about 1 minute and 18 seconds to respawn.
Each successful pickpocket grants 198.25 thieving xp one of the following for loot