• Many of his standing normals will miss on shorter characters, this is more notable on Octohead, but chars of similar size will probably have a similar issue.
• Shinkuu Tatsumaki is very inconsistent with how it hits characters. For example, it seems to work perfectly on Octohead, but it will push Ryu and KFM away after only a few hits and will get less hits than it should on Bad Mr. Frosty, I won't test it on everyone, but it should get all its hits in on everyone.
• Not sure if intended, but he can't do a single weak attack > medium attack > strong attack combo. His standing and crouching punches will always push the enemy too far away for his strong punches to connect, his medium standing kick simply does not chain into his strong kicks and his crouching weak kick doesn't chain into his crouching medium kick.
• "Get serious." "Get serious." "Get serious" really needs to go. It's better if the line only happens once in a while or if it doesn't happen at all and he just grunts when attacking.
• This is more of a personal preference, but I agree with N_N about the voice. SF2 voice would fit well because of the low quality, but the SF4 voice could also fit if you edit it to have a really bad quality like the other voices in ClayFighter. I also think that in both cases you could make the voice a little more accelerated, since the other characters do talk like they're in a hurry to finish their lines.
• Another personal preference, I think his Hadouken looks a little too... shiny and detailed compared to other ClayFighter projectiles, which are more on the simplistic side. It's also not transparent. I used Earthworm Jim's projectile to make a mockup of what I mean, I adjusted it to be more symmetrical (which Jin's isn't, but I think Ryu's should be) and to be roughly the same size as the regular Hadouken, if made sorta like that and transparent, it would be more fitting.

SF2 probably has the right kind of shading to more or less blend in with the clay characters. Might work even better if you bring down the color contrast or saturation.

Quick mockup: