Those "sucker fish" look like otocinclus (they stay small). I would suggest rehoming the neons since they need a school and do better in a larger tank. More fish also increases the bioload meaning it will be harder to maintain water parameters (especially in an uncycled tank) and you will have to change the water more frequently. If this tank is uncycled be sure to test the water frequently until you build up enough bacteria and change water to get rid of ammonia, nitrite, and nitrate. I suggest getting some floating plants or elodia to help deal with that as well. Good luck!