Hi i see the network of bitcoin have not many miners like i thought because of pools i guess, is it possible then
to start solo mining for example with 25 TH/s and catch block with little luck??
Thank you in advance for your time.
Yes it is possible with a little luck, with 25Thash of power you should reasonably be able to produce roughly 500 million shares or more a day. so feasably with some luck you could certainly hit a block.
Proof

for you "You can never solo mine its not worth it you will NEVER solve a block" Junkies. Here is how many shares it took for the last few block on the Bitcoin Affiiate Network Mining pool (The best mining pool in the world) i mine in who has had some pretty good luck past couple days.
332726 1,109,971,162 <-------- 1 Billion only
332719 67,048,976,224
332598 36,691,044,876
332497 342,491,990 <-------- 342 Million only
332496 27,023,335,912
So to honestly and unbiasedly answer your question YES with a little luck and 25 THS you Could, COULD, POSSIBLY solve a block.
You could also mine for 3 or more months and not solve anything