Is there? and if there is and if you reach it will you still be able to save your game or play it?
Yes there is a 999:59 limit though I don't know if you can't play after that. I think you can but it just won't count the time and if you save then it always saves at 999:59 http://chimchar.forumotion.com/t2392-hours-of-play-time-on-your-pokemon-games
No. You can play the as long as you want. However, Pokémon games for the Gameboy Consoles do run out when the internal battery has run dry, rendering it un-savable until you re-place the internal battery
On the screen, yes. 999:59. But you can play over that time, but the time will not be added.
Source
There is not max time. You can play forever. On my game on the startit says >play time: 999:99
xD