I apologies that the chronology itself isnt in chronology order, didnt even know what else to call it.
I have tried my level best to put it every major feat from Inbetweener be it high end or low end feats.
Warlock vol 1 09 : Inbetweener first appearance
Warlock vol 1 11 : Even Soul Gem proved ineffective against Inbetweener
Dr . Strange Master of the Mystic Arts 26: Ancient One think Inbetweener is all powerful
Dr. Strange Master of the Mystic Arts 27: Prelude to Inbetweener vs Dr. Strange
Dr. Strange Master of the Mystic Arts 28: Dr. Strange manages to beat In-Betweener by channeling the power of Lord Order and Master Chaos
Secret War 2 06: Beyonder explaining Inbetweener's place in cosmic hierarchy
Silver Surfer vol 3 16: Silver Surfer meets Inbetweener
Silver Surfer Vol 3 17:
Inbetweener enters 616 reality, fails to kill Galactus but plans to replace him. Summons Elder's anti-thesis, Lady Death and force her to kill the Elders. Death is upset but leaves without doing anything to Inbetweener
Silver Sufer vol 3 18:
Galactus vs Inbetweener, for reason unknown they choose to go pure h2h. The fight shakes the entire cosmos. Galactus is clearly getting the upper hand but is unable to actually finish him off, so they finally push Inbetweener back into his own universe were Lord Order and Master Chaos claim him.
Thanos Quest 01: Inbetweener vs Thanos, Thanos beats him because apparently in absence of imbalance between Chaos and Order, Inbetweener is powerless
Rom Vol 1 41: Dr. Strange vs Inbetweener, this time though Living Tribunal makes sure Dr. Strange cant call upon the power of Lord Order and Master Chaos themselves. The fight ends with a easy victory for Inbetweener
Marvel Universe the End 05: Inbetweener and well everyone vs Thanos with Heart Of the Infinity, still Thanos wins
Avengers vol 3 58: Half of Inbetweener is walking around and that is causing global chaos.
Avengers vol 3 59: Apparently Scorpio with a 13 Dimensional Zodiac key actually split open the Inbetweener, Avengers try to fight the inbetweener they cant, comes King Thor for help
Avengers vol 3 60: Thor hold his own against Order half of the Inbetweener, is even getting the better of him and then bam comes Wanda who beat both the Order half as well as the Chaos half of the Inbetweener. When Inbetweener is finally merged he teleports back cities on earth and fixes all the destruction caused.
Vengence 01: Inbetweener is seen as a teen-age boy here
inbetweener gets shot by this new character called Ultimate Nullifier and he finally evolved backs to his normal self
Avengers Assemble 07: Thanos win a cosmic cube ends the reality of elders one of whom is Inbetweener (it was later revealed the cube was fake and all Thanos manage to do was BFR the Elders)
Avengers Assemble 08: Turns out the cosmic cube was fake and all the elders are ok and Thanos couldnt even distinguish between a fake and a genuine cosmic cube, well F*&k you Bendis
Last Planet Standing 03: Inbetweener was among other cosmic beings as well as Living Tribunal who together attacked Galactus triying to destroy it but got hit by Reed Richards plasma canon and disappeared. This however is NOT 616 reality but rather Reality 982
Inbetweener was there to morn Eon passing during Infinity Gauntlet story arc.
What if Vol 2 75: Inbetweener was beaten and his power absorbed by Blink temporarily