All of them save perhaps 2, are irrelevant.
Parties of Personalities - Class III
Most of the parties are one-man show with delusion of grandeur and rational Singaporeans would never vote for them.
Tan Jee Say, Kenneth Jeyaretnam, Goh Meng Seng, and Desmond Lim are clearly persons of ego, and legends in their own mind. Benjamin Pwee doesn't come across as being in the same league as the rest in terms of ego. But I'm leaving him here for now, mainly because he is synonymous with the Democratic Progressive Party. I may be doing him an injustice, but it is a small injustice.
You can spot these personalities by their behaviour.
They flit from one party to another, but they fit nowhere because the only space that can hold their ego, is their own head. They join a party, usually with sincere intentions and dreams of turning a barely functioning party into one infused with their (imaginary) charisma and talent (also imaginary) and winning the election to govern Singapore.
And when they fail to "capture" an existing party, they will leave to form their own.
Initially, they may attract other opposition candidates who flock to them like a new hope. But once these "recruits" realise the ego they have to work with, they quickly drift away. Often because they have their own egos as well.
Or maybe, in one to one chats, they realise, "this guy is delusional!"
Or vice versa.
These are the Class III opposition parties.
Special Mention - Class II
Chiam's SPP, Chee's SDP, and NSP deserve special mention.
Otherwise, this would be a short post.
Chiam's SPP is a Spent Political Party. Its heydays are over, peaking in 1991 with 3 seats in Parliament.
Now he can offer the voters no future. This is evidenced by his 27 years in Potong Pasir, with attempts to recruit a successor, and failing. His final desperate attempt to hold Potong Pasir - field his wife.
He's is nice guy, a good man, and he had put a lot of effort into Potong Pasir. But he is not a leader. He can attract but cannot retain talent. There may be personality issues. He seems very independent and not one to delegate authority easily. Which may be why people leave. He cannot form a team because he is not a team player (maybe).
Chee "stole" SDP from Chiam many years ago. Chee was one of the first "successor" that Chiam sought to groom. But Chee has an ego and is also a legend in his own mind. Chee may fit well with the Class III parties, but in GE2011, it was the "Most Improved Party". (Actually I named them "The so-glad we're no longer the lose-iest party". )
So I am giving them the benefit of the doubt. But since then, they have lost Vincent, and Tan Jee Say. Not that Tan was a huge loss. But the party is down to Chee and... that's it.
SDP and Chee no longer pursues controversy and wild accusations. But you can't win votes with "vote for me. We're not crazy anymore."
[Edit 21 Aug: Aaaaand it didn't take long before they started testing the limits again. The spoof video... I can't comment on it because I didn't watch it. Maybe it's good. Or maybe it's cringeworthy. I do not know. I will check facts for my blog, but I draw the line at watching possibly bad videos. How do I know it might be bad. Chee made it. I think I have to demote them down to Class III.]
NSP had a lot of promise. May still have some promise, but is currently a third-rate political party. Which is sort of a compliment, because, those mentioned so far are fourth rate or lower.
[Edit 21 Aug: With the resignation of Hazel Poa, NSP has reverted to a party of old Egos. And with their decision to contest MacPherson with Steve Chia as the candidate... Well, it will be interesting to see what transpires. I believe Tin Pei Lin will hold and get more than 50% winning with a clear majority. WP will take 40%+. And Steve will lose his deposit. If Steve/NSP can pull a significant number of votes from WP, it would mean that they are still a viable party. This will establish the pecking order of opposition parties. But I think they have reverted to a Class III party of old egos.
Edit 23 Aug: And Steve changes his mind. OK. NSP is officially a Class III, fourth rate political party. Hmmm... not even sure it's a class III because it doesn't have the prerequisite "charismatic" (a.k.a. egoistic) leader.]
They were the sensational party of 2011 with their star Nicole Seah, but she has left and they seem bent on trying the same stunt again to get free publicity.
That seems like all flash, no substance.
The sad part is NSP may now simply be WP bird dog. Marine Parade GRC may be a case in point (or it may be a once-off situation). As the second most viable opposition party (though with no wins to show for it), WP can see where NSP has won about 40% or more of the votes, and target that ward as their next possible conquest.
There is a baseline of 30% of Anti-PAP voters. If NSP can attract another 10% (total 40%), that means the ward is prepared to consider a viable opposition. WP calculations then is that if WP contests in that ward, they might well be able to take the ward because of WP branding.
We shall see what the next elections brings.
Leading Party - Class I
This is of course Worker's Party, the winningest opposition party, the party that wrest the first GRC from PAP. Their place in history is assured.
At this point they are in an enviable position. With due credit to Low, he has built up a WP with a Brand. Quite a contrast to the WP under JBJ which was a party of personality then. It was All JBJ, All the time.
But now it has a brand, it has a viable, visible team, and alternative leaders. And at Punggol East By-Election, it showed that it could wade into a four corner fight and BEAT the PAP.
That's serious street cred.
That's so serious that when the other opposition parties called for talks to avoid multi-way contests, WP approach was basically, to let the other parties know where they were contesting and leave the others to get out of the way.
Because the simple reality (as proven at Punggol East BE), is that the Voters are discerning voters and know who or what they want. WP has got the signal. The other parties are pretending they didn't hear, and that they still have a chance.
The obvious reality is that the opposition talks to avoid multi-way contests were simply to ensure that the lesser opposition parties would not lose their election deposit. In any ward, there would be approximately 30% committed anti-PAP voters. They will vote for any party as long as it is not PAP. However, throw in two opposition (in a 3-way contest) and the anti-PAP voters will choose, and the lesser one will be disadvantaged to the point where they may well lose their deposit.
THAT is the real reason they needed the talks.
WP did NOT need the "horse-trading" talks. They can be assured that in any ward they choose to contest, they would NOT lose their deposit. In PE, they even proved that they could WIN against the PAP despite two potential spoiler opposition parties. As the ONLY credible opposition, in any contest they would be easily guaranteed about 30% of the votes.
If any other opposition tries to be spoiler in a ward WP were contesting in, there is a good chance that they would lose their deposit (again, PE BE). Hence, WP had no need to compromise with any other opposition parties.
Here's a video explaining why we would eventually have a two-party system, and the Spoiler effect (at about 5:05)