It grew up again and became taddy. You can see it wearing the ribbon that Robumi gave
Wasn't that the frog mum's original baby?? Im talking about the 2nd tadpole
There is no second tadpole, unless you're referring to the one that was just born in the last chapter. In chapter 16 we were shown Taddy leaving fully evolved, then when Robumi leveled up, Takashi summoned another monster again. He was wishing it to be like Taddy, and it turned out that what he actually summoned was Taddy who reverted back to it's unevolved form
WHAT HAPPENED TO THE SUMMONED TADPOLE???