DCA approach can only be applied to bitcoin, this is because bitcoin has great potential and is likely to be more valuable with the timeline as long as you are in a long term investment. Another thing you should know is that DCA approach can be done by both the pleb and the rich which any amount even as low as $10. It depends on how much your income is and how you feel is best for you to start investing with.
Shitcoins are useless and don't even deserve investing in because they are more like gamble and beginners don't need to distract themselves, talk more of DCAing on shitcoins. You don't need to look for any coin with big market capital, just invest in only bitcoin and DCA regularly with the amount that would be at ease with you after you have taken care of your monthly expenses and have made available your emergency funds.
If it comes to investing for long term and if it comes to coin selection and I am asked about it then Bitcoin would be the best choice for me without a second thought. Since we have bitcoins to invest in long term plans, we don't need to check any other coins. There is no need to waste time on choosing which coin for long-term investment, instead of wasting time, we have to close our eyes and trust Bitcoin. In case of long-term investing, when an investor is new to investing, he usually starts his investment journey with a relatively small amount of money at that time.
DCA method has the advantage of investing with minimum amount of money so it is very good for those who follow DCA method to invest in a good direction. If a person is involved in any other work resource then that person can easily build a good support for his investment by buying bitcoins in different steps.
It becomes easier for an investor to buy Bitcoin when the price of Bitcoin is at different stages. When the investor invests a certain amount of money consistently every month or every week, at the end of the specified period, it will be seen that his investment amount has increased.
When an investor has the idea that he has to deposit a certain amount of money at the end of every month or week, that investor will not waste money and will always try to spend within a limited range. We always hear about a problem that if we have money in hand we spend it without thinking much but if we have the thought of investment in our mind then we forget the extra cost and this is a very positive aspect for us.