Over GTS in Ultra Moon I got a Tangrowth. I figured I'd check it's stats and they were great. However, waiting until LV 40 for a Tangela to learn Ancient Power and evolve doesn't appeal to me. I've looked elsewhere, but I got vague answers at best. If it's possible, great then I can make a Tangrowth with amazing stats. If not, well, I'll still make the Tangrowth, but it'll be a bit weaker than I planned. Not a huge loss, but I'd like the stats to be as high as possible. Thank you for your input.
BTW, this is the Tangrowth I plan to make:
Tangrowth (Male) Function: Tank
Item: Big Root/ Assault Vest
You can also teach it Ancient Power via the move relearner on Mount Lanakila (in the Pokemon center).
To get Heart Scales, eat at a restaurant.
Source, Heart Scales Found Here and Here.
Hope I helped!