Check out the list of emulators recommended to TAS games for each platform in the official tas videos site: http://tasvideos.org/EmulatorResources.html

There are everything for old game platforms, like Atari, GameBoy, or MS-DOS.

For PC games on Windows only, there is a program called Hourglass: http://tasvideos.org/EmulatorResources/Hourglass.html The site itself doesn't really recommend to use it because it is an old program without any more support. You can search further about this program.

For flash games, I search a bit myself about that, it doesn't seem like a program to TAS flash games exist. Generally, you can use Cheat Engine to speed up or slow down some games, and you can also write automated scripts that execute button presses at exact times, but they can get out of sync really easy. I used such a script with AutoHotKey to do TAS for one browser game (which was made in html5, not flash).

i am really confused about the question here, first i thought you wanted a tas program and then you said you wanted to speedrun flashgames??

TASing is still speedrunning, it’s just another form of it. So the question still makes sense, it’s just better suited for TAS Videos as mentioned above.