Would you really give a non-transforming Transformer like a Mighty Mugg or a Titan to a infant??? I'd be looking for something age appropriate like a rattle or teething ring. As someone that works retail I'll tell you those sold to kids from 3 or 4 up to adult collectors.
Hasbro tried Build-a-droid multiple times over many years with the Star Wars line. It never worked out well for them and they have now seemingly given up on it completely. Speaking of Star Wars, that's how I think a line of Quintessons should be made. They should be a single wave of 5 Black Series 6 inch style figures if going for mass retail, or a box set if going for SDCC, HasCon or limited release retail.
I know a 3rd party made a full line of Quintessons long before the overpriced 3rd party craze took off with City Commander. I might go try to find a set of them.