Using Dhalsim is difficult - S Groove is a good groove for him provided you’re good at dodging and using his other attacks.
He has a teleport as well so don’t forget you can use teleport like a hindu dodge.
After dodging I usually either knee the person or teleport away.
Dhalsim has counters for almost everything so here is a brief run down on how to beat some of the more common characters.
Sagat: Use your zoning to keep him away but don’t be at complete opposite ends of the screen. If he throws his tiger fist at you just punch him it goes right under his projectile … this is why you can’t be at polar opposite ends. If he throws the low one you’ll want to jump straight up and teleport either forward or backwards … teleporting forward on the ground will bring you to close and teleporting backwards will have you reemerge into his crouching tiger fist unless you are against the wall to begin with in which case you’re just doing the Hindu Dodge. If he tries getting close you’ll want to fierce yoga fire followed immediately by a s.rh. If he jumps either teleport, knee, or yoga breath (hcb+k)
Bison/Balrog: Very easy to beat with Dhalsim as he has almost no jumping abilities. Just keep yoga firing and be fast enough to abuse Yoga Flame (hcb+p) since again almost all his attacks will be coming from the ground level. Since your using S-Groove dodge when needed and zone him back out or teleport yourself back out. Also abuse the YogaStream (hcf,hcf+p) once in the red area.
Sakura: Use the Yoga Breathe since most of her attacks will have her jumping up a little and the rest is pretty much like a weaker Sagat…
This is pretty much the basics so like when I say that for Sakura think about it for all characters that are going to be doing a lot of arial attacks.