can profesor x communicate telepathically outside earth without the help of cerebro like rachel did?

was he powerful enough to trap shadowking inside his head like psylocke did?

was he still the most powerful telepath before jean died?

He defeated a race of aliens with the power of love one time

i think Yes, he was the most powerful telepath. Jean was certainly the most powerful psionic... but that includes her TK - with which, phoenix boosted but not hosting, she was the premier wielder of. Only Shaman Nate gave her a run for that title.

He was powerful enough to trap Shadow King on the Astral Plane - and that was the first time he'd ever engaged in telepathic combat. There is absolutely no question that Charles is/was infinitely more powerful than Betsy.

Charles could communicate almost easily with Lilandra - in another Galaxy... so i think yes... super-earth telepathy is likely. He did also Communicate (or try to) with Galactus when the X-Men were trapped in the past on the Skrull homeworld (before the Devourer devoured it). Galactus was in space. Charles was on planet.

Xavier was the most powerful telepath but in the end he knew that in case of his demise he had to be sure that the other telepaths were strong enough to step into his shoes. i feel that he held alot of his power back especially since he was very confident that he could defeat phoenix scott, which i think he could have but he chose not to because he knew that he was standing in scott's way & the only way for scott to realize his true potential, his true calling xavier had to let scott kill him. xavier could easily do what the other telepaths had done over the year but again he held himself back while pushing them to be stronger and not have to rely on him

its pretty simple

Xavier > The rest :-p

@darthphoenix:

can profesor x communicate telepathically outside earth without the help of cerebro like rachel did?

was he powerful enough to trap shadowking inside his head like psylocke did?

In each of their encounters he's trapped Shadow King in the Astral Plane which Psylocke failed to due and had to sacrafice herself. Xavier was always strong enough to fend him off and trap him there.

was he still the most powerful telepath before jean died?

Nope Jean was his superior only in raw power and potential but Xavier had more experience and tenacity when it comes down to telepathy.