For a minimum, I'd say consult the Original Series. Charge lists on average have become rather longer since then. However, the point of a charge list is to establish that an OC is a Mary Sue and/or that the canon has been broken. You could rack up a million SPaG errors and still not accomplish that. Also, charging for the same problem (e.g. bad spelling) more than once is unnecessary and will just result in a wall o'text that no one will want to read.

See Also:

Charge
Charge List
Mission Writing Guide: "Okay, So You've Found a Badfic. Now What?"

~Neshomeh

So far, I have these. (This list is not limited to Grammar and Spelling.)

- Notably, there are several mentions of a "her", despite this story being in the First Person.

- The Main Original Character has a double-bladed Sword of Sueness, a Cute Animal Companion Horse, is the (human) daughter of Aslan and the granddaughter of Professor Diggory, and falls in love with Peter Pevensie.

- The following characters are brought out of character; The Professor is never supposed to be married to begin with, and even if he was, he would most likely not allow his daughter run away to Narnia- meaning, he would not be the kind of person to give her a reason to run; Peter never falls in love as far as we know, and most certainly, not very easily, if he did; Aslan is supposed to be the Narnia's version of Jesus, or God, or whatever, and he is portrayed as ignorant in a few cases, and his powers are greatly diminished as a result; Jadis is portrayed as a more dramatically evil character, as opposed to the stuck-up, cold and calculating villain she is supposed to be.

- Additionally, the Mary Sue has a problem with unnatural, sometimes forced dialog that really grinds my gears personally, and will likely irritate one of my Agents, and this Sue never learns any lessons, or has her character developed in any way, positively or negatively.

So far, those are all that I found.