Does orianna require a team comp to be viable?

No.

i really dont think so to me she is similar to cass but stronger.

Orianna doesn't require a composition around her. She's picked because she's a very generalist mage. She can make solo plays, can save champions, has decent zone control and kite mechanics, and scales well. If you're looking to do something more specific, you find mid laners who will bring you that power (i.e. Zed to solo kill/split push, Twisted Fate to lane shove and global presence, Syndra to 100-0 squishy targets, etc.). Orianna doesn't NEED Malphite or Jarvan IV, they simply amplify her strengths.

Shes viable in every team comp. point and click on frontliner,press R.

She's sleeper OP.

Farm. Use q, use R, use w. gg wp you killed most of their team and/or put them all at low hp.

No, but it doesn't hurt. The leash range on her E is a lot longer than the range of her Q, so it can let her initiate from a safer distance. Many other initiation ults also move faster than her Q can move the ball and CC the targets enough to keep them from escaping the brief setup time. You'll do fine without a Malph/Jarvan/Leona to stick the Ball up the enemy team's butt, but having one makes your job safer, easier, and more effective.

She's also much better with a team that can capitalize on the enemies being all grouped up, like a Sion or a Miss Fortune.

Theres an over focus on Ori landing that perfect ult because its potentially game turning. In reality, it pretty much require the enemy team to be stupid for Ori to land a 5 man ult regardless of what your own comp is. Even a 3 man ult is a good day. Getting two people is fine.

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Like would she need a malphite or jarvan to put the ball on to engage

I don't think it's required, but it helps.

She's not exactly an engage mage, since she typically builds glass cannon, and lacks major engage tools. But the god like engage coming from a ball delivery system, isn't exactly a requirement for Ori to be an effective member on a team comp.