do they

well im currently playing through it again and im now at the point of training in the world of ruin and i want to know do they get there hp to 9999 without bonusses like bahamut's hp +50%??

Some do (I seem to remeber Cyan) even without the Esper. Some don't.
The utility of using the Esper on everyone, though, is that once they've reached HP 9999 fast you can dedicate to other stats (like Magic Power) while leveling up. That's particularly useful if you're planning to use Genji Glove + Offering and 2 Ultima Weapons, since as we know the damage they deal depends on HP.

That's why I focused on attack or strength or whatever. That way they can deal full damage with just regular high-end weapons. My Sabin had the Gengi Glove and Offering with some Claw things and if there wasn't a limit on the amount of damage you could do he would have done well over 10,000hp damage. The gengi glove cuts your damage in half. And even at that he was doing 6,000+ per hit. A little better weapons a little more focus on his stats (I had to max out HP first >_>) though I was certainly not dedicated. A lot of the espers with stat bonuses I felt sucked so I didn't stick with them too awful long. But anyway, why would you want to train them without the added effects of espers? I always feel incomplete if my characters don't all have 9999/999

In all honesty, the few times I did take 'em to level 99, it didn't matter a bit if they had 9999 HP or 9700 HP, they still kicked ass. At that level, a couple more HP/MP or a couple more points on a stat isn't going to make much difference. Some got the level bonuses for Espers simply because they were learning magic when they leveled up.

well vyk thats just the point i want to use the espers for stuff like vigor and magic power and such and thats why i want to know if they reach max hp so i wouldnt need to give them hp bonusses

stamina is pretty much worthless, focusing on vigor and mgc.pwr is much more useful, and if you keep Odin a while, you can also boost your speed-stats (THATS pretty nice ;-))

Hmm... that would be nice.

Boost up Locke's speed stat. He'll steal more often (or so I think) and will go first most of the time.

my opinion is your wasting your time. the only 2 games where ive maxed a stat is. max health on ff7 and max hp and strength on ff 8 and maxed strength on ff 10 2. but there the easy ones so not much time was wasted.