Now this is a bitch of an achievement!! It isn't difficult but it is VERY time consuming. If you are prepared to put in 150+ hours on World Snooker Championship 2007 then you may unlock this achievement. (You will unlock other achievements in this 150+ hour stint also)
Here is my "career" championship route that I followed.
I started with the Snooker Championship and worked through 2 full seasons - ensuring that I won EVERY single match. To guarantee winning follow these instruction - If you are losing in a frame by an unassailable amount of points and there is no reasonable chance of getting snookers (remembering that the AI opponents are amazingly good at getting out of snookers) then go to PAUSE MENU to stop the AI winning, then press XBOX guide button and EXIT to dashboard and then reload. Make sure you enter Snooker Championship so as not to lose any progress. Now you WILL have to exit regularly, especially in the beginning. Now, after 2 full seasons of winning every tournament you should be in the Top 16 Ranking (very occaisonally a third season will be needed to get this rank) which will unlock 2 final tournaments. Just make sure to maintain your Top 16 Rank and win these competitions using the previous technique.
After Winning ALL Snooker Tournament achievements I started the Pool Championship. Again 2 FULL seasons of winning EVERYTHING will be required to get a Top 16 Ranking. This will unlock 3 final tournaments. Win these using the same "exit to dashboard" boosting method. At the end of the season make sure you have achievements for all Pool Tournament wins.
Back to main menu, select championship, then trickshot. None of these trickshots are particularly difficult, and with the skills and control you should have over the cue ball you should get this in approx 2 hours. It is a case of trial and error with the variety of spins, pace and cue elevation on these trickshots.
After Trickshot start a GOLDEN CUE tournament. This is a knockout tournament. You will play 5 frames of snooker, 1 frame of 9-Ball pool and 1 frame of 8-Ball Pool. Again use the "exit to dashboard" technique to guarantee wins. You need to win at least 4 frames to progress in any mix, eg. 2 frames of snooker, 1 frame of 9-ball and 1 frame 8-ball. Again, do this through EVERY round and win the Golden Cue competition.
Now, you should have won all Snooker, Pool, Trickshot and Golden Cue tournaments by now - but still no "Winner of ALL the Championships" achievement. Don't worry!! Despite this not being a tournament par se you must now start a Hybrid Championship season. You will be asked to select up to 10 competitions but to make it easy I only chose 2 tournaments - which were World Pool Masters and the US Open. Now play these through and make sure you win for max ranking points. After the 2 tournaments start a new Hybrid season when prompted and play the same competitions again. Now do this OVER and OVER and OVER and you will eventually get in to the Top 16 Ranks. Maintain Top 16 rank until the end of your 2 tournament season and you will unlock the WINNER OF ALL THE CHAMPIONSHIPS achievement.
At bloody last.......