Most powerful vs Most powerful?
Pre-retcon Beyonder vs Thanos w/HOTU Stalemate
Scathan vs Pre-retcon Molecule Man Pre-retcon Molecule Man
Protege vs Matrix Merlyn/Edifice Rex Protege
The Living Tribunal vs Nemesis The Infinity Being The Living Tribunal
Alien Entity vs Genesis Alien Entity
HOM Wanda vs Infinity Gauntlet Stalemate maybe IG
616Jaspers vs Jammie Braddock 616Jaspers
Nexus/Havok vs Galactus with the Ultimate Nullifier Nexus/Havok
Abraxas vs FP Meggan FP Meggan
Pre-retcon Beyonder vs Thanos w/HOTU = Stalemate
Scathan vs Pre-retcon Molecule Man = PR MM Unless Scathan has authority from TOAA to contain him.
Protege vs Matrix Merlyn/Edifice Rex = Protege
The Living Tribunal vs Nemesis The Infinity Being = Living Tribunal
Alien Entity vs Genesis = Stalemate. Both were the supreme beings within Marvel. Only difference is that Genesis decided to set back to the way things were before his journey whereas AE joined with the fires of creation.
HOM Wanda vs Infinity Gauntlet - Stalemate
616Jaspers vs Jammie Braddock - Jaspers
Nexus/Havok vs Galactus with the Ultimate Nullifier - G w/ UN
Abraxas vs FP Meggan - I will say Abraxas