It says on the wiki he barely defeated Yamcha and then was defeated by Tien's tri-beam/kikoho, so Tiencha should wipe the floor with him.
If trying to guess what Cell's PL would be after absorbing 17 and Krillin, I wouldn't expect him to get weaker since there's no precedent of getting weaker from absorption - actually, there is one, which is Buu getting weaker from absorbing the Kai. Was that just due to the Kai's good nature or did the Kai have some will to stop Buu that led to Buu weakening? If it's just the former, then it's possible for Krillin to weaken Cell due to him being a good person. It's less likely his will could affect Cell, since while he'd want to weaken Cell to help the Z fighters/Earth, he's not a Kai and has no magic powers so maybe he can't enact his will while absorbed. But either way, Kai didn't weaken Buu by that much, so Cell should still be stronger than 1st form Cell at least and would be way stronger than Tiencha. The only thing is if he can survive a barrage of tri-beams like 2nd form Cell did.