tfa bubblegum is like a very light, ambiguous fruit flavor to me. Sometimes mixing strawberry and peach, but especially strawberry and nectarine together makes both flavors disappear and this "bubblegum" flavor comes through. Dragonfruit in the mix in certain proportions evokes it too, I've noticed. Anyway, I like bubblegum flavor with lime and/or mint/menthol. It makes a nice simple, refreshing flavor.
I've never tried this, but for a more authentic bubblegum flavor you might take a page from HIC'S Dubble Bubble recipe and mix it with a small amount each of wintergreen and cinnamon.