Is there a tier list in Super Smash Flash

Not exactly, at least their arent any I've found. All of the characters have virtually same attack power and the only main difference is attack speed, so it would be hard to make a tier list for such a game...

Although... Through some testing via AI Melees, this is what I've gotten with all 28 characters:

It's read like this:
X-[Character Name] (Y-Z)
Where: X = Ranking Number
Y = Number of wins in the test
Z = Number of losses in the test


TOP TIER:

S Tier:
1-InuYasha (23-4)
2-Crono (22-5)
3-C. Falcon (22-5)

HIGH TIER:

A Tier:
4-Knuckles (21-6)
5-Blue (21-6)
6-Zero (20-7)
7-Kirby (19-8)
8-S. Sonic (19-8)

MID TIER:

B Tier:
9-Megaman (19-8)
10-Luigi (18-9)
11-Mario (17-10)
12-Mr. Incred. (17-10)
13-Cloud (17-10)

C Tier:
14-Mr. G&W (15-12)
15-Zelda (14-13)
16-Fox (13-14)
17-Naruto (13-14)
18-Sonic (13-14)

LOW TIER:

D Tier:
19-Tails (11-16)
20-Blade (9-18)
21-Samus (9-18)
22-Lloyd (7-20)
23-Shadow (6-21)

BOTTOM TIER:

E/Pokémon Tier:
24-Y. Link (4-23)
25-Mewtwo (4-23)
26-Pikachu (3-24)
27-Link (2-25)
28-Jigglypuff (1-26)

You can switch C. Falcon and Knuckles around (In fact, IMO Falcon should go right below Zero or S. Sonic, but this is based off the raw numbers), because, you know, Boulder Throw and stuff... and some chars should be higher, since this was done with the help of AI, and as we all know, the AI in SSF tends to be a bit over-reliant on the D-att, leading characters like Lloyd and Fox to have suicidal tendencies during these tests, and leading Pikachu to be a Thunder spammer, which in turn makes him fall to the bottom tier, even though he is actually Mid Tier material. But, aside from that, this is the closest to a tier list you'll find for SSF, since most people worry about the sequel now.