Udyr is great against him. Its just a farm lane. They can't kill each other.

Kog'Maw's existence counters Singed no matter how he builds.

As for solo tops, you might need to send a ranged champ up there to stop him or maybe a Yorick because Singed just doesn't die. Once he gets catalyst he just instantly grows massive balls and will harass you or dive you and there's very little you can do about it, especially if you're a melee champ.

The best thing you can do if you're paired against him is to deny him farm as much as possible because he needs a lot of it. Delay his RoA as LONG as possible because the longer it takes him to build it the longer he won't have the stacks up from it. RoA is usually a pretty bad item, but on Singed it gives him health from the health stacks AND health from the mana stacks because of his passive.

If you failed to stop his farm, tell your AD carry to build a bloodrazer. It's well worth the investment especially against a really beefy team.

Singed can easily be countered. Some good counters are Nidalee, Gangplank, Mundo, and Yorick. Many ranged ad champions can also defeat him. If you do not chase singe he will likely push your lane. Once your lane is pushed have your jungler come in to get the kill. If SInged can not farm he will not be able to tank later.

Yorick.

Singed counters melee champs, so pick a caster or a strong ad range.

Rumble is incredibly strong against Singed top lane.
-Rumble doesnt have to worry about mana and Singed does.
-Singed is fast and is often a threat because of his speed... but Rumble can sheild/speedboost to escape/chase. Rumbles harpoon can slow him down.
-Singed has to get into melee range to last hit creeps early. He also runs in to poison the creep waves. When he does this Rumble can just turn on the flamespitter for free damage.
-Rumbles Ult is really good against singed.

J4 Strong counter! when you do trades post 6 you can ulti him for no escaping.

That would secure your kill especially if jungler (with even more cc) would come.

Teemo, Kennen and Vlad all tend to crush Singed top lane. I've also personally had trouble with a well-played Garen, Irelia, Olaf, Renekton, Tryndamere, Warwick, and Yorick (Although I've also beaten some of those when they were played poorly).

I never have many issues as singed top against any ranged tbh once i get boots i can get to a ranged very fast, the one time i got completely countered is by Teemo. His W lets him be as fast (if not faster) than i am, he has ranged harrass and mushrooms he can just run around so that i can never get to him effectively. IMO Teemo is the best counter to him, yorick may also be a champion that is good but generally isnt that fast if you dont have speed runes so you may end up being killed anyway especially if a jungler ganks