How many average levels until evolve?

Question

I have a level 55 Dratini that I caught at Dragonspiral Tower and,this is also for any pokemon that evolves,it was supposed to evolve at level 30.If a pokemon is over its evolving level when you catch it,is there an average amount of levels to make it evolve.

Answer 1

Make it gain one more level and it will evolve this also goes for any pokemon that is over the level it is meant to evolve

Answer 2

If you level up 1 more time, it will evolve