Team Marvel Telepaths:

Jean Grey, Professor X, Legion, Doctor Strange, Mister Sinister, Adam Warlock, Apocalypse, X-Man, Franklin Richards, Moondragon

Team DC Telepaths:

Despero, Martian Manhunter, Darkseid, Doctor Destiny, Raven, Prescence, Obsidian, infinity Man, Brainwave

This is a telepathy battle only, no other powers can be used, which team will come out on top and can people give their reasons why?

I can't speak for all of Marvel's telepaths, but I can speak for Nate Grey. Nate's mere presence is enough to cause painful pyschic feedback as it's done to Psylocke (K/O'ed), Professor X, Jean Grey, and Holocaust. Mind you, he wasn't anywhere near them, they were in entirely different states across the country. Nate has manhandled Professsor X in a telepathic battle and even pulled his astral form out into the physical world, something he noted Phoenix didnt even do. Nate as a kid (7-10 years old) bypassed Mr. Sinister (AoA) telepathic defenses despite the fact Sinister had psychic dampeners in place. He's also upsurped Jean Grey telepathically on several occassions. Cable even stated that Nate already exhibits all of his psionic potential and then some. And his psionic power is equal to that of the Dark Phoenix Force. All of these feats are pre-shaman. As a shaman, he's reconnected a woman's fragmented mind from across multiple universes (Like 28). And he's also capable of draining telepaths of their psychic energy and using it to empower himself, as he did to an entire group of minds simultaneously. Nate is possibly the most powerful telepath on Marvel's team, Legion and Franklin Richards are the only ones close to him. Nate either outrights dominates them telepathically or absorbs their psychic energy, if that's allowed.

DC.

Isn't Legion like Galaxy-Universal with TP? Nate and Franklin are pretty insane, I would say that Despero is about on Nate's level, maybe a bit above.

Not sure why Adam Warlock is on Marvel Telepaths. He hasn't shown telepathy beyond mind reading without the soul gem and that was in his first form. He has good telepathy defenses, but that's it.