I would recommend getting up to speed with the Legislative process and administrative rule making process first. It's much more complicated than you think.
Of the species or groups of species you listed, one group (gars) is prohibited by state statute and regulation. Another group (FW stingrays) is prohibited only by state regulation. The third group (snakeheads) is regulated by state regulation and its importation and interstate transport is prohibited by federal law.
Cal. Fish and Game Code Section 2118 lists the prohibited species that the Legislature has deemed fit to regulate. Section 2118 also authorizes the Fish and Game Commission to pass their own regulations prohibiting additional species. The Fish and Game Commission regulations duplicate the statutory list found in Section 2118 and list a number of additional prohibited species or groups of species, including FW stingrays and snakeheads.
To legalize FW stingrays, you'd have to convince the Fish and Game Commission to promulgate a rule amending their existing regulation to exclude FW stingrays. To legalize gars, you'd have to: 1) get the Legislature to pass legislation and the Governor to sign such legislation amending the existing statute to remove gars and 2) get the Fish and Game Commission to promulgate a rule amending their existing regulation to remove gars. To legalize snakeheads, you'd have to: 1) get the Fish and Game Commission to promulgate a rule amending their existing regulation to remove snakeheads and 2) get the U.S. Fish and Wildlive Service to promulgate a new rule to amend their prohibition on importation and interstate transport of snakeheads.
I hope this helps.
