Genki Bakuhatsu Ganbaruger

Kids and their transforming robot will fight the enemy. 

Friendly and fun mecha action with bratty protagonists in a shouwa era setting. School life, friendship and family are often bigger themes than the alien/demon world invasions threatening earth. Both shows might appear old and outdated by today's standards, with oldand almost Disney-esque drawing styles, but are well worth checking out. 

Easy to digest shows with clumsy gradeschoolers being handed powerful weapons (giant robot / ancient energy weapons respectively) to fight equally clumsy adversaries in mostly "monster of the week" fashion. Simple but memorable character designs you won't see in any other anime. Very rewatchable. Despite the over the top settings, both shows manage to have very well made final arcs that still stay true to the show's formula. 

Similarities include: slapstick style humor, funny monster-of-the-week gimmicks, sympathetic villains, a funny and cute protagonist trio guided by an odd teacher figure, in the Super Robot genre in Ganbaruger's case (and more of a boy's focus.) and in the magical girl and fantasy genre in Chacha's case. 

Ganbaruger and Machine Robo are good animation robo shows with mecha ready to fight the enemy in a glorious high tide battle. 

Different genres and target audiences, but both series know when to be funny and when to be serious (with the overal tone favouring comedy). Similar "looming curse" and "know when to quit" moments in both shows. Outstaning endings in both cases.