When to use potential form vs dekiru?

[Kuromaku]

When to use potential form vs ~dekiru?

For example kakeru vs kakikotogadekiru.

[s1212z]

kakeru vs kakikotogadekiru.

You want dictionary form here, not stem form
書くことができる

Have you checked out the Readings section yet? There are several links, including a 30 min video (didn’t watch it). My understanding, ことができる is a bit more formal while the potential form has the flexibility for be inserted other common grammar points (such as potential v + ようになる).

Here is the grammar point discussion section for question postings:

ことができる - Grammar Discussion

can, be able to Structure Verb + こと・が・できる Noun + が・できる View on Bunpro

[Johnathan-Weir]

Additionally it seems ことができる implies more of an ability whereas potential form can mean a particular instance.

i.e.

映画を見ることができる。
“I can watch the movie” (I have eyes and there are places I could go watch it, etc)

vs

今日は映画が見られないけど明日は見られる。
“I can’t see the movie today but I can tomorrow.”