"* riding *" implications.

For the sake of standardization if nothing else:
 
ponies riding ponies should imply pony, riding  
humans riding ponies should imply human, riding  
ponies riding gators should imply pony, alligator  
ponies riding dragons should imply pony, dragon, riding  
humans riding horses should imply human, horse  
horse riding a horse should at least imply riding  
ponies riding griffons should imply pony, griffon, riding  
ponies riding dinosaurs should imply pony, dinosaur, riding  
humans riding humans should imply riding, human  
ponies riding cats should imply pony, cat, riding  
dragons riding dragons should imply dragon, riding  
ponies riding pokémon should imply pokémon, ponies, riding, crossover  
ponies riding bulls should imply pony, bull  
humans riding griffons should imply human, griffon, riding  
ponies riding bears should imply pony, bear, riding  
anthros riding ponies should imply pony, anthro, riding  
pokémon riding ponies should imply pokémon, ponies, riding, crossover
 
There are more tags along these lines, but these are all the ones with at least ten hits.