tangela does not have an evolution
Tangela will only evolve if you level it up once it knows ancient power (which it learns at level 33). take it to the move maniac to make it learn it if you didn't teach it to tangela.
you get it to a certain level
33
At level 33, Tangela learns 'Ancient Power'.If Tangela levels up while it knows 'Ancient Power', then it will try to evolve into Tangrowth.
Tangela has to level up while knowing the move Ancientpower.
Tangela > level up while knowing Ancientpower > Tangrowth
When Tangela wants to learn Ancient power let it learn it, then level it up again and he/she will evolve into Tangrowth.
33 or34
Tangela > level up while knowing Ancientpower > Tangrowth
Tangela will evolve at any level if it knows the move Ancient Power.
Tangela evolves when it has ancientpower and level it up.It learns ancientpower at level33.