So just out of curiosity how do you determine what characters will be clone options for us to vote on?
great question
1. the character is a canon part of its own franchise
Example: Travis from Mother 4 is not an option
2. the clone can either reasonably share the bone structure or moveset of its original character
Example: Ganondorf is a large muscle-bound man, much like Captain Falcon
3. the clone is a part of the original character's franchise
Example: Samus only got Metroid characters as options
Exception: Ice Climbers, Game and Watch, and ROB are counted as "retro" because this opens their options significantly
4. Must at least be visually distinct from the original character
Example: Doctor Mario may be Mario, but at least he doesn't look the same
Note: this is kept within reason, Mario's vacation outfit from Sunshine may look different but there is no real direction to go in with an alternate moveset. On that note...
5. must have some direction to go with for a moveset, even if slight
Example: Claus is probably physically identical to Lucas, but it is stated and shown in Mother 3 that he is more energetic and aggressive
Exception: Star Fox characters
6 (sorta). preferably, the character should not be implied, stated, or shown to be objectively or canonically better or worse than its original
Note: this rule has been demoted to a simple preference, as it used to be the reason mega pokemon and Fierce Diety Link were not in polls. Still, I highly prefer to avoid this since a character that's objectively better seems more suited to an overpowered PSA while a character that is objectively weaker is better suited for a joke character
7. not previously established but I'll say it here for future polls. The character should not have a well-updated or recent moveset made for Project M, and/or a significant number of movesets on the vault period. Should this rule be broken, I should do everything I can to differentiate myself from it.
Example: Young Link, Doctor Mario, and Shadow all break this rule
Exception: Dark Pit
Exceptions currently in polls: Shadow, Metal Sonic, and Ninten are all in polls despite breaking this rule. You may notice none of them sound similar to the most updated PSA, however.
Sometimes a character may break one or two rules but get a free pass due to ease of development or other factors that justify its inclusion anyway.