Fight takes place on an empty street, 20 feet apart. No morals, fight to the death. No blitzing.
It's definitely sinister then - Glads can be beaten by psychic assaults, and, based on the recent appearance in Uncanny X-Men 1-4, Sinister definitely is packing some serious psychic firepower. on top of that, as I said, the fight is to the death - Glads can stalemate at best given Sinister is immortal. Glads would also probably lose confidence over time, given that he can never actually kill Sinister, until his confidence hits zero and Sinister could probably overpower him at that point too. Or Sinister could kill Glads' confidence level through telepathy. Without speed blitz and with the fight to the death, this is one-sided in favor of Sinister
I think Sinister would win here, but I want to get more clarity on Sinister's durability, which seems to be normal human level now, and cloning. In the past, his body was physically malleable and could reform, but with this past incarnation in Uncanny, he had numerous clones that he was able to transfer his psyche to each time he was destroyed. IIRC, he incinerated himself and then another clone body was created, with multiple dead Sinister bodies lying around as he repeated this process. When he fought the X-Men after he stole/took over the Celestials tech, he was taken out by basic attacks (i.e. - a bullet through the head by Hope killed his clone), so his durability doesn't appear to be superhuman anymore, but that he can clone himself repeatedly. If he can continuously clone each time he is destroyed, and since he is immortal, and with powerful TP, I think he would win. Gladiator is TP resistant (he resisted Rachel Grey before) but I think Sinister's TP is at or near Xavier level, and will eventually overcome Kallark's mind, or diminish his confidence to weaken him and then kill him.